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TOPOGRAPHIC MAPS 
and SKETCH MAPPING 



BY 



J. K. FINCH, C.E., A.M. 

Associate Professor of Civil Engineering and Resident Director of the Summer 
School of Surveying, Columbia University in the City of New York 



FIRST EDITION 



NEW YORK 

JOHN WILEY & SONS, Inc. 

London: CHAPMAN & HALL, Limited 

1920 



v* 



tf&p 



^ 



Copyright, 1920, by 
J. K. FINCH 



MAR 18 1920 



PRESS OP 

BRAUNWORTH & CO. 

BOOK MANUFACTURERS 

BROOKLYN, N. V. 



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©CU566115 



PREFACE 



The demand for instruction in map reading and sketch 
mapping, brought about by the Great War, has led to the 
development of a course on this subject in many of our colleges 
and technical schools which have assisted in preparing men 
for the various officers ' training camps. Outside of the 
purely military field our universities have in the past found 
it necessary to develop a course of this character for students 
in Geology and Physiography who are required to make 
extensive use of topographic maps. In recent years the 
development of the automobile and the camping habit has 
led to a more extensive use of maps by the general public, and 
a large number of people have " disco vered" our own United 
States Geological Survey Maps, but are still unable to under- 
stand them completely and to make the fullest possible use 
of them. 

It will doubtless be necessary in the future for many edu- 
cational institutions to continue instruction in this subject 
for students taking reserve officers' and other military train- 
ing courses in connection with their regular college work. 
Furthermore it seems probable that in many of our insti- 
tutions the demand and necessity for such a course will lead 
to its inclusion as a regular academic study, given perhaps 
as a part of the instruction in Geology or Geography, or as 
a separate course under Civil Engineering. It is with this 
idea in view that this volume has been prepared. 

A large number of educated people have never learned to 
use topographic maps because it has been the general opinion 
that considerable mathematical knowledge was necessary. 
This is far from true. During the past few years it has been 
necessary to give instruction in this subject to a great number 



iv PREFACE 

of men who never went beyond "plain" geometry, who passed 
this point many years ago and claimed to have forgotten all 
they ever knew of mathematics. They have picked up the 
subject quickly and are generally the most interested students 
and do the best work. This has been particularly true of work 
in sketch mapping and in several cases men have stated 
that they intended securing the simple Army sketching 
outfit and using it on summer outing and camping trips. 
Indeed there is no reason why work of this kind could not be 
made part of the instruction in the summer camps for boys. 
Interesting applications could easily be worked out and it 
would doubtless stimulate interest in the practical mathe- 
matical problems. 

The author had the pleasure of cooperating with Dr. 
Charles P. Berkey, of the Department of Geology of Colum- 
bia University in giving the course on "War Topography," 
originated by Dr. Berkey for the Students' Army Training 
Corps. The notes prepared for this course have formed the 
basis for the present work. The author takes pleasure in 
acknowledging his indebtedness to Mr. F. K. Morris, of 
the same department, with whom he cooperated in giving a 
similar course, for many ideas of value. Mr. Morris has 
also contributed a Descriptive List of the Principal Topo- 
graphic Maps of the World, which will be found in the ap- 
pendix. This is believed to be the most complete list of 
this kind which has ever been published. A number of the 
questions following the first sections are based on the mimeo- 
graphed notes prepared for infantry and field artillery candi- 
dates at Fort Sheridan, Major Cromwell Stacey, Senior 
Instructor. 

J. K. F. 

New York City, 
August, 1919. 



CONTENTS 



PAGE 

Introduction ix 

Kinds of Maps. — Government Maps. — Map Reading. — Sketch Mapping. 
— Landscape Sketching. 

PART I. MAP READING 

CHAPTER I 
WHAT A TOPOGRAPHIC MAP SHOWS 

ItT. 

1. Topographic Maps. 1 

Use. — Military Maps. — Essential Features. 

2. Title and Marginal Information 3 

Map Sheets. — Name. — Index Maps. — History. 

3. Conventional Signs 7 

Clearness and Detail. — Characteristic Sheets — Conventional Signs of U. S. 
G. S. — For Large Scale Maps. 

4. Conventional Signs. — Continued 11 

Ordnance Survey of British Isles. — Car.e de France. 

5. Relief. 18 

Methods. — Hachures. — Spot Heights. — Contours. — Principles of Contours. 

6. Relief. — Continued . 25 

Contours on Maps. — Drainage and Ridge Lines. — Contours and Drainage. 

7. Relief. — Continued 28 

Estimating Heights from Contours. — Elevation of Points between Con- 
tours. — Underf eatures . 

8. Relief. — Continued 31 

Relief Models. — The Layer System. — Oroscopic Maps. — Shading. 

9. Direction 36 

Arrows or Pointers. — The Compass and Declination. — Meridian from the 
Sun. — From the North Star. — Compass Bearings. — Surveyors' Method. — 
Azimuth. 

10. Scale 42 

Representative Fraction. — Scale Equivalents. — Conversion of Scales. — 
Scales Used for Maps. 

11. Scale. — Continued 46 

Graphical or Reading Scales. — Scaling Distances. — Construction of Graph- 
ical Scale. — Accuracy of Scaled Distances. 

v 



vi CONTENTS 

CHAPTER II 
HOW TO GET CERTAIN INFORMATION FROM A MAP 

ART. PAGE 

12. Sections and Profiles 51 

Sections — Construction of Profiles. — Scales. — Profile Paper. 

13. Slopes 55 

Slope Angles. — Slope Fraction or Ratio. — Grade Per Cent. — Conversion. — 
Practicable Slopes for Various Operations. 

14. Slopes. — Continued 59 

The Slope Scale. — Construction of Slope Scale. — Use. 

15. Intervisibility 62 

Topographic and Military Crests. — Dead Ground. — Intervisibility of 
Points. — Curvature of Earth. 

16. Visibility of Areas 66 

Use.- — Method of Plotting Dead Ground. — Landscape Sketch from Map. 

CHAPTER III 
USE OF TOPOGRAPHIC MAPS IN THE FIELD 

17. Coordinate and Grid Systems 72 

Descriptions. — The English Grid System. — The French Coordinate 
Method. 

18. Use of Maps in the Field % 76 

Orienting the Map. — Location of Observer's Position. — Resection, 

PART II. SKETCH MAPPING 

Introduction 81 

Use of Sketch Mapping. — Instruments. — Practice. 

CHAPTER I 
TOPOGRAPHIC DRAFTING 

19. Freehand Lettering 83 

Form of Letters. — Guide Lines. — Hints. — Spacing. 

20. Topographic Drafting 85 

Conventional Signs. — Signs for Sketch Mapping. — Relation of Size and 
Scale. . 

21. Enlargement and Reduction 87 

Use. — Methods. — The Method of Squares. 

CHAPTER II 

FLAT MAPPING 

22. Surveying and Mapping 90 

Mapping Methods. — Mapping by Distance. — Traversing. — Triangulation. 

23. Pacing and the Scale of Paces 93 

Methods of Pacing. — Pacing on Slopes. — The Scale of Paces. 



CONTENTS^ vii 

ART. PAGE 

24. The .Sketch Case and Traversing 96 

The Sketch Board. — Use of Alidade. — Methods. — Traversing with Sketch 
Board. — Error of Closure. 

25. Location of Details 103 

Radiation Method. — Intersections. — Offsets. — Field Procedure. 

26. Position Sketching 106 

Triangulation. — Base Line. — Development of Triangulation Scheme. — The 
Three Point Problem. 

CHAPTER III 

CONTOUR MAPPING 

27. Contour Interpolation Ill 

Drainage Lines. — Controlling Points. — Interpolation of Contours. 

28. Determination of Elevation 115 

Difference in Elevation. — Leveling. — The Slope Board. — Use. — Reduction 
Diagram. 

20. Contour Mapping ' 122 

General Plan. — Hints. — Field Procedure. 

PART III. LANDSCAPE SKETCHING 

Introduction , 125 

Use. — A Map in a Vertical Plane. — Steps Necessary in Making Sketches. 

30. Delineations and Perspective 127 

Delineations and Outlines. — Effect of Distance. — Perspective. — Vanishing 
Point. 

31. The Sketching Screen 131 

Construction. — Use. — Guide Points. — Steps in Working Up a Sketch. 

32. The Sketch Pad 133 

Description. — Method of Using. 

83. Descriptions and the Mil Scale 136 

Direction. — Target, Range and Deflection. — The Mil Scald 

APPENDIX 

1. A Descriptive List of the Principal Topographic Maps of the World. 

By F. K. Morris 139 

2. Suggestions for a Course in Map Reading and Sketch Mapping 166 

3. Bibliography 168 



INTRODUCTION 



A map is a conventional picture of a portion of the earth's 
surface as seen from directly above, showing more or less 
completely the various features of the country represented. 
Thus a land map may show only the boundaries of a certain 
piece of property and would consist simply of a series of lines 
forming a closed figure with the lengths and directions deter- 
mined by the surveyor — in short a conventional outline of 
the property in question. On the other hand, a complete 
"topographic' ' map, such as would be used in planning a 
landscape design for a park or estate, for example, would 
show every detail of the property — houses, roads, streams, 
and even, in some cases, individual trees as well as the relief, 
or ups and downs of the land surface which form its hills 
and valleys. Between these two extremes are all sorts and 
kinds of maps used for various purposes. 

Maps may be divided into two main classes — flat maps and 
maps showing relief. The former class embraces most of the 
maps with which we are familiar. They may show the principal 
features such as cities, towns, railroads, roads, rivers, streams, 
etc., but make no attempt to show the mountains, hills and 
valleys. In some maps the main mountain ranges are shown 
by a form of shading and, as the scale or size of the map in 
relation to the ground represented becomes larger, it is pos- 
sible to give with increasing accuracy the relief, and to show 
more and more of the details of the country. Thus it would 
not be possible to show on a map of the United States, say 
twelve inches long, much more than the boundaries of the States, 
the main rivers and large mountain ranges, and to indicate 
by small circles their principal cities. If this same size, twelve 
inches, is used to represent a few acres of country it is prac- 
ticable to show nearly all the details mentioned for the land- 
scape map above with the relief so clearly shown that small 



x INTRODUCTION 

inequalities in the land surface of a few feet in height would 
be accurately indicated. 

Practically all the nations of the world have either made 
or are now making topographic maps of their land possessions. 
These maps are generally published in sections and show a 
portion of the land surface drawn so that one inch on the 
map represents about a mile of land. In Europe the making 
of these maps has been largely inspired by military con- 
siderations. In the United States the main object has been 
to furnish maps suitable for the economic development of 
the country, the study of its geological structure and resources 
and the planning of engineering projects. For this reason 
our maps, published by the U. S. Geological Survey, are not 
good maps for military purposes, but they do show very clearly 
the relief which is of great importance in engineering work. 
Such European maps as the French and German show every 
detail of military importance, but the relief has been shown 
largely by line shading which is easy to understand but not 
very definite or accurate. Greater care in showing relief was 
thought to be unnecessary and these maps were well suited 
to the tactics of open warfare which prevailed up to 1914. 
Modern warfare, however, tends to settle down to intensive 
action along almost fixed lines with a great deal of engineering 
construction in the form of trenches, mines, etc., and any 
advance must be preceded not only by the accumulation of 
vast quantities of stores and construction equipment behind 
the lines, but also by the complete planning of the engineering 
features of the construction to be done as the troops advance. 
For this work neither the size nor method of showing relief in 
vogue in Europe before the war was suited, so we have seen, 
since the war began, the issue of new, larger and more detailed 
maps of much of France in which the accurate American con- 
tour method of showing relief is used. 

The ability to understand a topographic map and make 
use of the data shown in answering various questions in 
regard to the country represented is required of every officer 
and even the non-commissioned officers in the United States 
Army. The study of maps with this end in view is generally 
termed "Map Reading" and its importance m warfare will 



INTRODUCTION xi 

T)e readily appreciated when we think that every tactical 
movement, varying in size from the movement of an entire 
army down to a trench raid, is not only planned on a map 
but orders are issued with reference to a certain map or maps. 
Map reading may be divided into two parts. A. A study 
of the method of representing features on a map and B. How 
to make use of the map to obtain certain information. 

Map making is primarily the field of the engineer, and in 
modern warfare they are usually prepared by a special engineer- 
ing force trained and equipped for this purpose and assisted 
by aeroplane observers. Accurate up-to-date maps were found 
to be so important on the western front that specialists were 
developed in all the branches of the work from the purely 
engineering features of surveying to the interpretation of 
aerial photographs and the printing of the final map. New 
maps of active sections of the front were printed right behind 
the lines with field equipment and issued almost daily. In 
many cases large size maps were not available and officers 
had to make their own sketch maps to serve until better maps 
could be made and issued. This was particularly true in the 
recent activities on the Mexican border and in the campaigns 
in the Far East where, good maps had never been made. It 
has thus come about that officers in our army must not only 
be able to use maps, but to make them, and for this purpose 
the Army Sketch Case has been developed. A similar simple 
outfit is used by many geologists for field work in new country 
which has never been fully mapped. Such work, while not 
highly accurate, furnishes valuable information for various 
purposes, and is covered by the subject of Sketch Mapping 
given in Part II. It is part of the required training for all 
infantry officers. Artillery officers have to go much deeper into 
the subject and, while sketch mapping will furnish an excellent 
start, it will be found advisable to follow it up with a thorough 
course in surveying and the use of the surveyor's instruments. 

The subject of Landscape or Panoramic Sketching dis- 
cussed in Part III is primarily of military importance. Simple 
sketching of this kind, however, is a very interesting pastime 
and will be found of value in illustrating geological and other 
reports and as an aid in visualizing topographic maps- 



TOPOGRAPHIC MAPS AND 
SKETCH MAPPING 



PART I 
MAP READING 



CHAPTER I 

WHAT A TOPOGRAPHIC MAP SHOWS 

Art. 1. Topographic Maps 

As has already been pointed out a topographic map is a 
conventionalized picture of a section of the earth's surface 
as seen from directly above. In fact a good topographic 
map shows the surface features of the country represented so 
perfectly that it is possible to make an exact model of the 
country, called a relief map, from it. Topographic maps 
have important uses both for civil and military purposes. 
Every road, railroad, canal, dam or bridge is first planned and 
laid out on a topographic map. On these maps the engineer 
studies out his problems in construction, determines the best 
location for his railroad, the best location and spans of his 
bridges, even the location of his construction plant and camp. 
The geologist also uses topographic maps in studying physi- 
ography and working out the relations between surface and 
underground structure. Indeed it is easily possible to form 
a very clear idea of the age of the land forms and the character 
of the soil, behavior of streams and sub-surface waters and the 
underground structure of any section of country from a topo- 



2 WHAT A TOPOGRAPHIC MAP SHOWS 

graphic map. This subject, which is properly a part of the 
study of Geology and Physiography, is known as Map Inter- 
pretation.* 

For those who enjoy the open and wish to study and know 
the country traversed in auto trips or on camping excursions 
a topographic map is the best possible guide. 

In military work the necessity of complete, up-to-date 
military maps has been noted. These military maps are 
simply topographic maps to which additional information of a 
military nature has been added. They guide the operation 
of parties in the field, give positive information about the 
country in advance, and serve not only as a basis for planning 
all military movements, but also for directing artillery fire. 
In connection with the latter it should be noted that in 
modern warfare the target is seldom visible to the gunner and 
the direction and range which are required in aiming the gun 
are very often taken directly from a topographic map. 

There are five essential features or divisions of a topo- 
graphic map. 

(a) The Title, showing the location of the country 

represented — when the map was^ made — who 
made it, etc. 

(b) The Conventional Signs, by means of which the 

various features, such as streams, towns, roads, 
etc., are represented. 

(c) The Pointer or Arrow, by means of which the map 

may be properly oriented and directions deter- 
mined. 

(d) The Scale, which shows the relation between lengths, 

or distances, as they appear on the map and the 
actual distances on the ground. 

(e) The Relief, or the method of showing the shape, 

slope, and height of the hills and valleys. 

* See "The Interpretation of Topographic Maps" by Salisbury and Atwood. 
Prof. Paper No. 60 U. S. G. S. also "Military Geology and Topography," Edited by 
Prof. Gregory. Yale Press. 



TITLE AND MARGINAL INFORMATION 3 

Art. 2. Title and Marginal Information 

In former times it was the custom to make the title of the 
map a very elaborate affair which occupied quite a portion 
of the sheet and was highly decorated. With the adoption 
of rectangular sections for maps this practice could no longer 
be followed and the name, characteristics and history of 
the map, which make up the title, was, of necessity, placed 
around the margin of the map. 

Extensive topographic maps are made, as has already been 
noted, in sheets varying usually from 15 to 20 inches in height 
to 20 to 30 inches in width. When these sheets are bounded 
by meridians and parallels of latitude they are only approxi- 
mately rectangular, due to the fact that they represent a por- 
tion of the curved surface of the earth which is shown on a 
plane. Most systems of projection,* or methods adopted 
to show on a plane surface the meridians or parallels of the 
globe, require that the meridians at the top of the map be 
closer together than at the bottom for maps of the northern 
hemisphere and the reverse for the southern. Such maps 
cannot, therefore, be fitted exactly edge to edge so as to lie per- 
fectly flat, but may be made to do so by leaving a small space 
between the vertical edges. In other cases the edges of the 
maps are not based on latitude and longitude lines but are 
perfectly rectangular. The meridians and parallels of latitude 
when shown will, therefore, not be parallel to the edges of 
such maps. The International Mapsf and our own U. S. G. S. 
maps are examples of the former system and the English, 
French and German of the latter. In connection with longi- 
tude it should be noted that the origin is v seldom stated. The 
meridians on English and American maps are based on Green- 
wich as the origin while the French use Paris, Italian Rome, 
arid German Ferro. 

Each of the sheets of a given country is given a name or 
number, or both, which is printed on the margin of the sheet. 
The name given is either that of the principal town or topo- 

* See "A Little Book on Map Projection" by Mary Adams. London 1914. George 
Philip & Son. 

f See appendix for description of principal government topographic maps. 



WHAT A TOPOGRAPHIC MAP SHOWS 



INDEX TO 

THE ORDNANCE SURVEY 

OF 

ENGLAND 

On the scale of 

One inch to a mile 

Large sheet serle* 



SCILLY IS. 




8 CALE OF MILES 
5~ 10 20 30 40 i 



Fig. 1. — Index Map. Ordnance Survey of Great Britain. 



INDEX MAPS 5 

graphic feature on the sheet. It is obviously necessary, in 
order to select the sheet covering any particular section, to 
have some system of naming or numbering these individual 
sheets, of which there are 273 in the "Carte de France," 697 
in the old "one inch" series of the Ordnance Survey of the 
British Isles and several thousand for the U. S. G. S. maps. 
For this purpose Index Maps are issued showing a large 
section of the country with its main features, and the out- 
lines of the sheets with their names, numbers or both. See 



^ 



(Tarrytoivn) 



(Brooklyn) 



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6 


7 


8 


11 


fllli 


13 


20 


21 


22 



Carte de France. Amiens Sheet. 



U. S. G. S. Harlem Quadrangle. 

Fig. 2. — Methods of Indicating Adjoining Sheets. 

Fig. 1, which shows the index sheet for some of the English 
Ordnance Maps. 

It is also the custom to give on most maps the names or 
numbers of adjoining sheets. This is done either by printing 
the names of these sheets on the margin of the map, as in the 
U. S. G. S. maps, or by a small index map on the margin show- 
ing the numbers of adjoining sheets. The latter method is 
followed on French and English maps. See Fig. 2. 

The term "characteristics" was used above to cover the 
marginal information relating to the scale of the map, the 
north point or direction, data concerning the elevations 



6 WHAT A TOPOGRAPHIC MAP SHOWS 

and relief and conventional signs. These features are dis- 
cussed in succeeding articles and will not be taken up here 
except to note that this information really forms part of the 
title of the map. 

The history of the map is also noted more or less com- 
pletely. This may cover 1, the name and officers of the or- 
ganization issuing the map, 2, the names of the topographers 
in charge of the parties which made the surveys for the map, 
with the sections surveyed by each party indicated by a small 
key map, 3, the date of issue of the original edition and sub- 
sequent editions of the map, and 4, a note of the date of 
revision. The first of these history notes is valuable in telling 
us the origin of the map and from whom additional sheets 
may be obtained. The third is important in referring to 
certain maps, as considerable changes are frequently made 
in the manner of printing, etc., of different editions. "Pro- 
visional Editions" are also frequently issued which may be 
either compiled from the best available information, as is 
the case with a number of the English International Maps, 
or may simply indicate a cheaper edition produced by a more 
rapid and inferior process, as has been done with the Carte 
de France. The date of issue or revision is obviously of 
great importance in using the map as topographic features 
change from time to time when new or better roads are built 
and other public works carried on. This feature is particularly 
important on large scale maps which show a large amount 
of detail that changes quite rapidly. The importance of 
constant revision of the maps used in detailed military opera- 
tions such as were involved in the battle-fields of France 
in the Great War has been noted. The issue of up-to-date 
maps almost daily was made possible by the use of photo- 
graphs taken by observers in aeroplanes. 

In addition to the above data it is the custom of some 
countries to print the price of each sheet on the margin. 
Our own U. S. G. S. maps have printed in gray ink on the 
back, an outline of the work of the survey, forms in which 
the maps are issued, and how to obtain them, as well as a 
quite complete table of conventional signs. 



CONVENTIONAL SIGNS 7 

Art. 3. Conventional Signs 

The large number of natural and artificial features that 
go to make up the topography of any section of the earth's 
surface requires a corresponding variety of signs or symbols 
for their representation on maps. This necessitates not 
only the use of symbols of various forms and shapes, but also 
different colors, and even the thickness of lines and the style 
of lettering have their significance. In fact it is necessary in 
many cases to leave out a number of these features on maps 
of a small scale, such as most of the government maps, where 
one inch on the map usually represents about a mile on the 
ground. On any map we must seek a balance between 
clearness, legibility and the amount of detail that can be 
shown, bearing in mind the use to which the map is to be 
put. The U. S. G. S. maps are a good example of clear- 
ness and legibility and the elimination of a great deal of 
detail, while the German maps are filled up with such an 
amazing number of signs that a magnifying glass is neces- 
sary in using them and the main topographic features are 
so blended in and covered up that they are not prominent 
and obvious. The former maps, as has been mentioned 
before, are not primarily for military purposes. Only a 
few sheets have been printed showing vegetation* and on 
all sheets there are only two symbols for roads. This road 
feature* is probably their weakest point and renders them 
almost useless in picking automobile routes. On the other 
hand European maps make a great point of roads and are 
more widely used than our maps by tourists. 

It should also be remembered that the cost of a map 
involves not only the cost of the original work but also the 
cost of keeping it up to date by printing revised editions 
which changes in the topographic features make necessary. 
Large scale maps with many signs showing great detail are 
not only expensive to make but show features that change 

* See for example the Canaseraga and New Berlin Quadrangles, New York. The 
new military maps of the U. S. (see War Dept. Bulletin No. 64) to be made in coopera- 
tion with the U. S. G. S. contain this feature as well as a distinction between the first 
class and secondary roads. A few of these sheets, identical in other respects with the 
U. S. G. S. map, are already issued. 



8 WHAT A TOPOGRAPHIC MAP SHOWS 

so frequently that it is necessary to revise them almost yearly 
in order to keep them correct and up to date. 

It is obvious, therefore, that the number, size and char- 
acter of conventional signs will vary with the scale of the 
map and the object for which it is made. It is customary 
to print a special "characteristic sheet" giving the various 
conventional signs, lettering, etc., and on each map sheet 
the principal signs used on the sheet. It is desirable, how- 
ever, to have a fairly accurate knowledge of these signs so 
that constant reference to the marginal key, or "legend" 
as it is sometimes called, is unnecessary. Furthermore some 
maps such as the Carte de France and the German maps give 
no such legend and a key is absolutely necessary in using 
them. The principal signs used on American , English, and 
French maps will be described briefly.* 

The feature of relief is sometimes included as a conventional 
sign but is here treated separately. 

United States Geological Survey. The principal signs used 
are shown in Fig. 3. A large number of additional signs 
have been approved by the U. S. Geographic Board for use 
by all map making departments of the government including 
the military. These are printed in full in the "Topographic 
Instructions of the U. S. Geological Survey," where they 
occupy some nineteen pages, and also in War Department 
Document No. 418. With the exception of those shown here- 
with, which are the signs that are common on the U. S. G. S. 
sheets, these signs are not very extensively used. 

The signs used cover land boundaries, survey points, roads, 
buildings, water features, etc., and are printed in black and 
blue. Only two signs for roads are shown on the U. S. G. S. 
maps as noted above. A sign for metaled roads (identical 
with that of the French National Road, see Fig. 5) has been 
adopted and it is hoped will be used in the near future as 
a better designation of the kind of road represented is much 
to be desired on these maps. Triangulation stations and 
bench marks are permanent points, usually marked on the 
ground by tablets, and used in making the survey for the map. 

*For complete comparison of practically all government signs see "Military 
Topography." Hagadorn. 



CONVENTIONAL SIGNS 



Wagon-roads. 



Secondary & Private Roads-___ 

Road Crossings =3^— 

Grade — mm- 

Above Grade , , , , 

Below | i i i 

Trails 

Tunnels 






, Single Track 



Double Track >ri 1111 \ \ 1 1 1 1 1 1 III I II 1 1 HI 
Railroads (Two Railroads ' . ' !% '| ' , ' i * i ' t ' i ' t ' I* t ' i ' i ' i ' I * i * i * 1 ' j ' 




Cemetery. 



....... ffi 



Located Township and_ 
Section Corners 

Triangulation Stations - 



Bench Marks 

Mines and Quarries 
Prospects 




Streams 

Intermittent Streams -"'«— — v-.-'^l..- ~-H 

Springs and Sinks Jt 

s._ ijjp ^ 

Falls and Rapids. . 




Glaciers 






Fresh Marsh . 



Salt Marsh 



Tidal Flats. 



Dry Lakes 

Aqueducts 

Aqueduct TunnelB. 
Ditches and Canals . 



Light Ships _£ L.s. 

Light Houses... ^ L,H ' 

Life Saving Stations • >»8.8. 



State Line - «— 

County" : — 

Township Line — 

Reservation Line — 

Land Grant Line .- — — 

City, Village and Borough Line - 

U.S. Township Line - 

U.,S. Section Line _ 



Fig. 3.— Principal Conventional Signs of U. S. G. S. 



10 WHAT A TOPOGRAPHIC MAP SHOWS 

The height of the latter above sea level is indicated by the 
figures. The blue color used for "hydrography," or water 
features, makes them easily distinguishable. 

Note in connection with these maps that special forms of 
lettering are used for civil divisions (state, county, town, 
cities, etc.,) for hydrographic features and for relief. 

QUESTIONS 

Refer to Fig. 13, p. 28. Note that in using this map the brown relief 
lines are not referred to. They are explained later. 

1. Are the Western Maryland and the Baltimore & Ohio single- or double- 

track roads? 

2. How many bridges and tunnels are there on the Baltimore & Ohio 

within the limits of this map? 

3. Are there any means for transferring trains, from one of these lines to the 

other? Where? 

4. Are there any locks or tunnels on the C. & O. Canal? 

5. What is the character of the road between Hansrote and Magnolia? 

6. What is the dotted line running from Magnolia up the map? 

7. Assuming five people per house what is the population of Hansrote? 

8. Is there a railroad station at Hansrote? At Baird? 

9. In what way does the road cross the river between Orleans and Little 

Orleans? 
10. What is the small symbol about J inch from the left edge and 1 J inches 
above the bottom of the map? 

Large-scale Maps. As an example of large-scale maps 
the Hunterstown sheet of the Gettysburg- Antietam War Game 
Map will be found in the pocket in the back cover. This map 
was made at the Army Service Schools, Fort Leavenworth, 
Kansas, and is based on the work of the U. S. G. S. Note 
that points on the map are described by marginal letters 
and numbers. Thus Hunterstown is described as D-5, mean- 
ing that it is on the level of the marginal letters D on the 
sides and about on a vertical through the numbers 5 at the 
top and bottom. Note the conventional signs for this map 
which are shown in Fig. 48. The signs for out buildings can- 
not always be distinguished from houses as they frequently 
do not print clearly. Points where large streams are less 
than 5 or 6 feet deep are indicated by dots. Note also that 
the points of the toothed symbols used for cuts and fills 
always point down the slope. Vegetation that is insufficient 



CONVENTIONAL SIGNS 11 

for concealing troops is shown by the cultivated field sign 
while corn is specially noted. These features of the map 
would of course vary from year to year. The following ques- 
tions refer to this sheet: 

QUESTIONS 

1. What is represented by the rectangular groups of circles one and one- 

half inches to thelleft of Guernsey? (A-8.) 

2. Is there underbrush in the woods below and to the right of Texas? (C-8.) 

3. Is there underbrush in the woods one and one-half inches to the right of 

Goldenville? (C-8.) 

4. What vegetation is there in the field below and to the left of Goldenville? 

Below and to the right? 

5. What vegetation is there in the field left blank below Heidlersburg? 

(A-5.) 

6. Can you hide on top of the hill numbered 664 near Hamilton? (D-8.) 

On hill 592 near Good Intent S. H. ? (C-7.) 

7. Where is there a ford across the Conewago? 

8. Is Opossum Creek more or less than 15 feet wide? 

9. Is there a cut or a fill on the railroad at Guernsey station? (A-8.) One 

inch below Guernsey station? 
10. What is the straight saw-toothed sign leading up and to the left from 
HersheyMill? (B-6.) 

Art. 4. Conventional Signs — {Continued) 

Ordnance Survey of British Isles. Fig. 4 shows the char- 
acteristic sheet for the maps of this survey in most common 
use — namely, those drawn so that one inch on the map rep- 
resents a mile on the ground. Four editions of these maps 
have been published — one in black, one in color and two 
other editions, or variations, in one of which the relief is shown 
by hill shading and in the other by the layer system, both of 
which methods are described later. 

Roads are divided into four classes and one feature peculiar 
to these maps is that roads with fences on the sides are shown 
by continuous lines, while unfenced roads are shown by dotted 
lines. In the colored edition first- and second-class roads 
are filled in solid in an orange red. 

The sign used for railroads is also peculiar to British 
Ordnance maps. That for single lines is identical with the 
narrow gage railroad sign of the new French maps. We also 



12 



WHAT A TOPOGRAPHIC MAP SHOWS 



note on these maps that "cuts and fills" are shown. Cut- 
tings are places on roads or railroads where it has been neces- 
sary to excavate a trench through a hill, and fills are embank- 



ROADS 



1st Class 

2nd " 



•a (Altitude) 211 £ 



4th " (un-metalled) !7. 

Footpath 



ts rrrs^s: 




RAILWAYS 

_ , ,. Stations 

Two and more lines. 

Single lines 

MineralJines and Tramways ,, 



Tunnels 

Viaducts 

Embankment , CBDCffBSm ' 

Cutting > 

Roadway over railway. 

" under if 

Railway over railway 

Level crossing 

Electric Railways are treated as ordinary Railways 




Canal and Locks^ 
Aqueduct 



Windpump 
Windmill... 



Church or Chapel with tower. t 

" " " " spire t 

" " " without either .+ 



Post Office at Villages P. 

Post and Telegraph Office do. T. 



Letter Box. 
Milestone 



.L.B. 
5 

_-_.H6 



Heights in : 

Contours in feet ' "^ o 

or | 7l3200_ — •tl'.'m 
Trigonometrical point _ , A 



Lake 



ORNAMENT 




WOODS fcc^^ 
Deciduous....... s '■"?,«% *<«2?vs*>- 



Mixed.. 



Rough pasture- 




-rsmmk 



_ ^gru^-ou^ 



>= '.tsi:^ _.>r^. 



Gravel pit_ 
Quarry 



p -® 



BOUNDARIES 



County 

Parish 

County and Parish. 




Strean»_ 
'* d *i5fart"3a» °**lSiS* V> Bridge 



Ferry 
(Vehicles) 



Fig. 4. — Characteristic Sheet for English Ordnance Survey. 

ments built to carry lines over valleys and other depressions. 
These features are important from the military standpoint 
as they would furnish cover for troops and in engineering 
work they show whether it is possible for a road to cross a 



CONVENTIONAL SIGNS 



13 







Fig. 5. — Portion of the Swansea and Merthyr Tydfil Sheet (No. 102) of the 
Ordnance Survey of England and Wales. Scale 1 in. = 1 mile. Original in colors. 



14 



WHAT A TOPOGRAPHIC MAP SHOWS 



railroad, for example, either above grade (overhead crossing) 
or below grade instead of using the objectionable grade (or 



ROADS (CHAUSEE) 
National Highway. ■ 



Departmental- 
Good Road 

PooreiL__ 



Cart Track.. 



Old Road 

Path 



Trees on sides of Road... 



RAILROADS (CHEMIN DE FER) 

Single Track. I I 1 I I I I I I I 1 I I 1 

Double .. „_________ ____ 



Narrow Gage 
Tunnel 



Embankment 

Cut ~ — WMMEEMB - 

Station « on Onre 



TT 



RIVERS, ETC. (RIVIERE) 
Large River_ 

Stream 



©anal. 



WOODS, ETC. (BOIS) 



Woods o' •!%':• j v- 



Orchard 

Trees along stream 

Meadow 

Park 



BUILDINGS, ETC. 



Houses . 
Church 



n n 

-o 



Church used as survey point q 

Chapel J 

Cemetery E+J 

Water Power Plant jl» 



Windmill 



Empire- 



>£ 



BOUNDARIES 



Departments 

Arrondissements 

Cantons 

Communes 



Q Fontne £ p uit% 

Wells, etc. os ce 



Prefect fip|f] Sub-Prefect <®g> 

„ . ,Mu mil. Chief Town of Canton. (PTJ 

Survey Station £± 

Fig. 6. — Principal Conventional Signs of the Carte de France 

level) crossing. The use of a special sign for these features 
is common on European maps and in the detailed maps 



CONVENTIONAL SIGNS 15 

used on the Western Front in the Great War special attention 
was given to showi ag all cuttings and the depth was also 
indicated. 

Water features are shown on the colored edition in blue, 
streams less than 15 feet wide being shown by single lines 
and wider streams by a double line with water lining. 

Woods are shown by small tree symbols, the area covered 
being also tinted green on the colored maps. Tree signs 
symmetrically arranged indicate orchards. Parks are shown 
by a stippling of black dots. Fences are shown only when 
outlining the area of woods, parks or estates. Buildings are 
shown by solid black rectangular shapes, a post office being 
marked by a P, telegraph by T, and a letter box L. B. 

One interesting point is the use of a certain style of letter- 
ing for antiquities, such as Roman and Druidical remains. 
Egyptian capitals are used for Roman, old English for remains 
not Roman, but prior to 1066 (Battle of Hastings) and Ger- 
man text for the period 1066 to 1688. 

QUESTIONS 

Refer to Fig. 5. 

Note. — In using this map neglect all the shading and curved lines which represent 
the hill forms. These will be explained later. 

1. Is there any difference between the road going toward the upper left- 

hand corner (Swansea Valley) from Neath and that going toward the 
upper right-hand corner? 

2. Do these roads have fences on each side or are they unfenced? 

3. How many kinds of railways are shown on this map? 

4. What are the faint horizontal markings slightly above the center of the 

map? 

5. What do the dozen peculiar marks two and a half inches below the top 

of the map and one inch in from the right edge represent? 

6. What do the two letters L and B near road one-half inch in from upper 

right-hand corner represent? 

7. What is the character of the church at Neath? 

8. Point out a road that is unfenced? 

9. Point out a road fenced on one side only? 

10. What is represented by the fine black dots covering the area to the right 
of Neath near the reservoirs? 

La Carte de France de VEtat Major. This is the principal 
map of France, conceived by Napoleon and has been the 



WHAT A TOPOGRAPHIC MAP SHOWS 




p IG# 7 —Portion of the Amiens Sheet (No. 12) of the Carte de France de l'Etat 
Major. Scale 1 : 80000. 



CONVENTIONAL SIGNS 17 

inspiration for many European surveys.* Fig. 7 shows a 
typical section of this map which is printed in one color only, 
and Fig. 6 gives the principal topographic signs. 

Note that railways having two or more tracks are shown 
by solid lines of varying thickness depending on the number 
of tracks. Single-track lines are shown by the same symbol 
which is used on the U. S. G. S. maps. Care must be taken 
not to confuse cart tracks with narrow-gage railroads. The 
latter will usually run out from main lines. Note also that 
a new feature is introduced on the road signs which have 
small dots on either side representing trees. Do not confuse 
these dots with those used to indicate a commune boundary, 
which also frequently runs along a road. There is practically 
no difference between the "Route Nationale," which is main- 
tained by the State in excellent condition, and the "Route 
Departmentale," which is differentiated from the former 
solely for administrative purposes. 

Windmills are shown by a special sign which is simpler 
than the English, and churches which have been used as 
survey points in making the map are also specially indicated. 

The various boundary lines are carefully indicated and the 
principal town of each canton is indicated by an oval enclos- 
ing the letters C. T., while the Bureau de Prefect, Bureau 
de Sub-Prefect, etc., are also shown in a similar way. The 
forest signs are much like the English. 

A few abbreviations are used on the English maps but 
French maps contain many, the meaning not always being 
plain. Chau = Chateau (mansions), Chnee = Cheminee (fac- 
tory chimney), Min = Moulin (mill), etc.f 

QUESTIONS 

Refer to Fig. 7. 

Note. The black shading lines representing hills should be neglected. They 
are explained in Art. 5. 

1. Is there any difference between the two roads leading to Fienvillers 

(lower left) from the left? 

2. What are the three peculiar signs about one-half inch below Candas 

(lower center) ? 
* See Appendix. 

f See "Aids to the Use of Maps employed by English, French, Belgian, and Ger- 
man Armies." By Thos. Drew. London: Jarold & Sons. 



18 WHAT A TOPOGRAPHIC MAP SHOWS 

3. Is there a cemetery at Longuevillette? 

4. Are there any industries served by water power along the Authie River? 

5. What is represented by the dots surrounding Candas? 

6. What is the small triangular mark just across the railroad from the num- 

ber "153" above Candas? 

7. What do the abbreviations stand for just above and below this number? 

(See 6.) 

8. What is the character of the road from Brisbergues (left center) to Fien- 

villers? 

Art. 5. Relief 

Three methods, hachures, contours and shading, have 
been used on maps either singly or in combination to show 
the relief, or variations in the height of the earth's surface, 
which form hills and valleys. The method adopted to show 
the relief must indicate clearly three things: 1, the shape and 
size of the hills; 2, the slope; and 3, the height of the ground. 
While the contour system does all three of these things with 
the highest accuracy of any method yet devised it has the 
disadvantage of being harder to understand than the hachure 
or shading systems. It is more difficult to form a mental 
picture of what the ground represented looks like, that is, 
it is more difficult to visualize the relief from a contour map 
than from these other forms. Accuracy is so important in 
these days, however, that contour maps are gradually coming 
into wider use and various aids, such as shading, colors, 
etc., are sometimes used to assist in visualizing the relief. 

The hachure method doubtless originated from the out- 
lines and shading which were used to show hills on the birds- 
eye- view-maps of the 16th and 17th Centuries.* As finally 
developed they consist of short shade lines running directly 
down the slopes of the hills, that is, they show the direction 
in which water would flow down the hill. The shape of the 
hill is thus quite apparent from these lines (see Fig. 7). The 
slope of the hill is indicated by the thickness and spacing of 
the individual hachure lines. A steep slope is indicated by 
heavily inked lines very close together. Darkly shaded areas 
therefore indicate steep slopes, while lightly shaded portions 
are gentle slopes, and level areas are left without any shading. 

* See Hagadorn, "Military Topography," for reproductions of some of these maps 



HACHURES 19 

The exact height of the ground is only shown at important 
points on hachure maps. This is done by means of "spot 
levels" or "spot heights" scattered over the map and giving 
the height, or elevation, of certain points. Thus, referring 
to Fig. 7, which is a hachure map, the height of Fienvillers 
(lower left) is 153 meters above sea level as indicated by the 
number "153" or spot height, just to the left of the town. 
In connection with the Great War these spot heights were 
frequently used to describe hills that had no other names. 
Thus "103 Meter Hill" simply meant a hill having no name 
but shown with a spot height of 103 on the map. In naming 
hills in this way it is of course necessary to state also the 
locality, as there may be a number of hills of this height. 
The hachure method is very common in European maps, 
being the method used for the Carte de France, the famous 
German 1 : 100,000,* as well as the British Ordnance maps 
(see Fig. 5), in the latter case combined with contours, how- 
ever. The disadvantages of hachures are the facts, already 
noted, that while they indicate very clearly the general form 
of the ground they do not give as definite information as 
contours do, and that they, cover up the map and obscure 
the other details in hilly country. 

The contour system is used on the U. S. G. S. maps, 
Japanese Government maps, on the German and Swiss 
1 : 25,000* maps, in conjunction with hachures on the English 
Ordnance, with shading on the new French map (see Frontis- 
piece) and the maps of Norway, and with both hachures 
and shading on the latest edition of the German 1 : 100,000 
maps. The principles of contours will first be discussed, then 
the various aids to their use explained. 

Contours appear on maps as curving lines, in some places 
close together and in others far apart. Frequently they form 
closed figures of irregular shape and in many cases they do 
not close at all but pass off the edges of the map. These lines 
on the map represent imaginary lines on the ground that 
possess this peculiarity, namely, they join points which all 
have the same elevation. When we find a contour line num- 
bered 1000 this means, therefore, that every point on this 

* This refers to the scale of the map which is discussed in Art. 10. 



20 WHAT A TOPOGRAPHIC MAP SHOWS 

line is just 1000 feet or meters, as the case may be, above the 
zero level, which is usually the level oi the sea. Contours 
are sometimes described as successive shore lines and it is 
true that the zero contour will be a shore line and that if we 
imagine the level of the sea to be raised 1000 feet the new 
shore line will be the 1000-foot contour and similarly for other 
contours. It is clear, therefore, that a man walking along the 
side of a hill and always staying at the same level, going 
neither up nor down, will be tracing out a contour line. 

(a) _^ 




Fig. 8. — Showing Principles of Contours. 

Some of the fundamental characteristics of contours 
can be shown by the experiment illustrated in Fig. 8. 

(a) Shows a perspective view of a box the front of which 
is glass and in which there are placed three solids as shown, 
a right cone, a slanting cone and a hemisphere. The bottom 
of the box is assumed to be sea level, the zero level. Water 
is put in the box so as to fill it to a depth of 10 feet and the 
new shore lines on the solids are drawn and marked "10." 
Another 10 feet of water is then put in giving a total depth 
of 20 feet and resulting in the shore lines marked "20." This 
procedure is followed until the solids are all submerged. If 
we look down on the tank from directly above, the successive 



PRINCIPLES OF CONTOURS 21 

shore lines on the solids will look as shown in (6). The three 
series of curves in (6) are therefore the contours of the three 
solids and the numbers on these contours indicate the height 
of the contours or shore lines above the zero level. Bearing 
this experiment in mind we can understand the following 
definitions. 

The zero level is known as "datum." It is the level from 
which heights are measured. The numbers on the contours 
are their "elevations, " that is, their heights, or distance 
measured vertically above the zero level or datum. 

The depth of water was increased by 10 feet each time to 
secure the successive shore lines or contours. The difference 
in elevations or vertical distance, between any two adjacent 
contours, is therefore 10 feet. This difference is known as 
the "vertical or contour interval" (frequently abbreviated 
to V. I.). On most maps the V. I. is the same for all the 
contours, but in some maps such as the International Map* 
it varies, and only the 100, 400, 600, 1000, etc., contours, for 
example, may be shown. 

In reference to the datum it should be noted that the con- 
tours will be exactly the same whether the datum shown is 
used or any other datum differing from it by a multiple of 
the V. I. Only the elevation of the contour will be changed. 
Thus if we consider the water surface when there is 10 feet 
of water in the box as the zero level, or datum, the contours 
will all be the same but will be numbered ten less in each case, 
while the present zero contour will be an underwater contour 
and should be marked —10. If the level is assumed as zero 
when there is 15 feet of water in the box then both the con- 
tours and their elevations will be changed. Their shapes 
and spacing will remain the same, however, and they will 
be simply new curves drawn half way between the old ones. 
It is thus apparent that while it is interesting to know how 
high we are above sea level, and therefore to use maps for 
which the datum is sea level, that no important difference 
will be apparent in the contours if any other zero level is 
used. The marginal information on a map usually states 
the datum and gives the V. I. 

* See Appendix 1 . 



22 



WHAT A TOPOGRAPHIC MAP SHOWS 




(a) 




(&) 




Fig. 9. — Models for Contour Drawing. 



PRINCIPLES OF CONTOURS 23 

In connection with the contour elevation it should be 
noted that it must always be evenly divisible by the V. I. 
as it is simply a multiple of it. Thus we cannot have a 355- 
foot contour if the V. I. is 10 feet. \ 

Referring again to Fig. 86 it is seen that the contours of 
the right cone are all concentric circles, and are evenly spaced, 
as the slope of the cone is the same all around and is uniform. 
Those of the slanting cone are ellipses and are spaced closer 
together on the right-hand side than on the left, as the slope 
is much steeper on the former than on the latter. In the case 
of the hemisphere the contours are all concentric circles, but 
the spacing varies, indicating that the slope is the same all 
around but is steep near the edges and flatter near the top. 
Hence we may say that contour lines close together indicate 
a steep slope and far apart a gentle slope, and that when they 
are evenly spaced the slope is straight, or uniform. It is also 
true that two contours of the different elevation will not ordi- 
narily meet or cross. If, however, the right face of the second 
cone had been vertical the contours would all merge and if 
it had overhung the lower contours would curve inside of 
the upper ones. In nature this condition occurs only in those 
places where we have vertical or overhanging cliffs. 

QUESTIONS 

Questions 2 and 3 refer to Figs. 9a and 96. These are photographs of 
plaster models* and the exercise consists in drawing sketch contours to 
represent the forms illustrated. Assume that a V. I. of one inch is to be used 
and that the contours are to be drawn one-half the actual size of the model. 
Exact contours could only be drawn from measurements of the model itself, 
but sketch contours can be made from the Figures which will properly express 
the form of the models, the shape, relative slopes and heights. 

1. Draw contours having an interval of one inch to represent a pyramid 

(square base with four sides equally inclined and terminating at the 
top in a point). Base is six inches square and height six inches. 

2. Fig. 9a shows an island consisting of a hill of simple rounding form with 
a varying slope. The hill is 6| inches high and 10 inches long. 

Fig. 96 shows another island consisting of two connected hills of different 
height (6| and 7| inches, respectively) and with several steep valleys 
running up from the sea. The model is 14 inches long. 
Refer to Fig. 13. 

* See Appendix 2. 



24 



WHAT A TOPOGRAPHIC MAP SHOWS 



Hill Top 




^RDS EYE VIEW SHOWING CONTOURS 




— After Byrant and Hughes 
Fig. 10. — Contours and Contour Map. 



CONTOURS AND DRAINAGE 25 

4. What is the V. I. of this map? 

5. Which hill has a steeper slope, that above Magnolia (lower center) or 

that below, directly across the river? 

6. Which is higher? 

Art. 6. Relief — (Continued) 

Fig. 10 shows a bird's-eye view of a section of hilly country 
with the corresponding contour map below. It is seen that 
contours in nature never have the perfectly regular shapes 
of Fig. 86 and furthermore they do not always form closed 
figures on the map. It is true that a contour must always 
close and form an irregular shaped closed figure but all con- 
tour lines do this only on maps of islands or entire continents. 
For example, every 10-foot contour would not close on a map 
of the United States, one would simply pass off the edges of 
the map as it would take a map of both North and South 
America to show this contour completely. 

In studying Fig. 10 we therefore note that a number of 
the contours pass off the edges while others representing 
hills with downward slopes in all directions form closed figures. 
Portions of the land surface which project above the surround- 
ing country, such as mountains, hills or knolls, and that 
are entirely within the limits of the map, will have closed con- 
tours. The dotted black line shown on the map, which prac- 
tically coincides with the skyline in the bird's-eye view, marks 
the "divide" between two watersheds. That is, all surface 
water below this line on the map will drain through the small 
watercourses into the larger stream shown at the bottom of 
the map. The drainage of the area above this line will be 
toward the top of the map into the watershed of which only 
the upper ends of two small streams are shown. Running 
out from this main divide line are some minor spurs and 
ridges which run down the map from the hilltops. In con- 
nection with the lines of the divide and these ridge lines it 
will be noticed that they are higher in certain places than 
in others. The high points are hill tops and the sags are 
known as saddles, or cols. 

Fig. 11 shows the relation of the drainage and ridge lines 
for the country mapped in Fig. 10. Streams are shown by 



26 



WHAT A TOPOGRAPHIC MAP SHOWS 



solid lines and the divide, ridge lines and spurs are dotted. 
It will be noted that the ridges form valleys in which the 




Fig. 11. — Relation of Drainage and Ridge Lines. 




Hilltop 



Saddle 



Saddle? connec On g fw o h i lis 




,o^ ! 



Contours at a stream: 




•„<&■ 



Contours on a ridge- 



Fig. 12. — Characteristic Contours. 



streams are located. Some of the valleys are not sufficiently 
large to maintain streams, but in general the streams are 



CONTOURS AND DRAINAGE 27 

separated by ridges and there is a branching ridge system 
which fits in between the branches of the drainage system. 

A study of the behavior of the contours at streams and 
ridges as illustrated by Fig. 10 shows that contours curve 
or bend upward, or toward the higher ground, at streams, 
while the opposite is true on ridges, that is, the curve of the 
contour points down the slope. 

Fig. 12 shows the characteristic contours for hilltops, 
saddles, streams and ridges. While the type of drainage and 
relief described above is a common one there are many others, 
and the various sheets of the U. S. G. S. should be studied, 
along the lines above indicated, so as to bring out the rela- 
tion of drainage and relief. This is one of the most important 
steps in developing an ability to visualize the country repre- 
sented by a map, as well as in analyzing the relief for the 
purpose of mapping. 

QUESTIONS 

1. In the same manner as required in the previous questions referring to 

Fig. 9 draw sketch contours for Fig. 9c. This shows a model of a steep 
coast with a headland (about 3^ inches high) running out into the sea. 
The outer end of this headland has been cut off so as to form a steep 
cliff. Note that most of the contours will run off the map as the model 
represents only a short length of the coast and does not show the spurs 
back to the top of the mountain range. 

Refer to Fig. 13. 

2. Point out a saddle on the ridge below and directly across the river from 

Magnolia? (Lower center.) 

3. Do the contours to the right of Magnolia show a knoll? 

4. Place a piece of tracing paper over Fig. 13 and draw the line of the Potomac 

River and the divides and main ridge lines (all minor ridges not 
required) in a similar manner to Fig. 11. 

5. Outline on a piece of tracing paper the drainage basin, or watershed, 

of the stream flowing to the right, then downward, and entering the 
Potomac almost opposite Baird (left center). 

6. Referring to Fig. 7 place a piece of tracing paper over this hachure map 

and draw the drainage and ridge lines (see Fig. 11) of the rectangle 
above and to the right of Longuevillette. 



28 



WHAT A TOPOGRAPHIC MAP SHOWS 



Art. 7. Relief— (Continued) 

Contours alone will not give the exact heights of hill- 
tops. We can estimate the height of any point from the 
contours, but the exact height of an important hilltop, when 
given on a contour map, is shown by a spot height as on a 
hachure map. For example, the elevation of the peak below 
and to the left of Piney Point is given as 1988 in Fig. 13 (lower 
right). 

To estimate the height of a hill when no spot level is 
given we proceed as follows. The highest hill on Fig. 10 must 
be over 130 feet as the 130 contour is shown below the top. 




By F. K. Morris. 
Fig. 13a. — Birdseye View of Country shown by Map, Fig. 13. 



& 



Also it must be less than 140, as the V. I. is 10 feet and no 140 
contour appears. The best estimate would probably be 135 
feet. A rough profile of the hill, such as is described later, 
will frequently lead to a closer estimate. 

Depressions or basins below the general ground surface 
would be shown by closed contours just like hilltops. If the 
elevation of every contour was always given the relative 
heights could be easily determined. It is common practice, 
however, not to number all contours and on U. S. G. S. maps; 
every fifth contour is drawn heavier and numbered. For 
this reason, and in order to make it clear when a contour shows 
a depression below the general ground level, short lines are 
drawn on the inside of the depression contour (pointing down 
the slope) similar to the lines used for embankments, but much 




Fig. 13. PART OF PAWPAW QUADRANGLE. MD.-W. VA. U. S. G. S. SCALE, 1 : 62,500 



CONTOURS AND ELEVATIONS 29 

shorter. There is thus a special depression contour sign.* 
A special hachure sign is also employed for cliffs on contour 
maps, and sand dunes, etc., are shown by fine stippling. 

It is sometimes necessary to get the elevation of points 
between contours, and this is also done by estimation on the 





(6) 
Fig. 14. — Underfeatures. 



assumption that the ground has an even slope between the 
contours. This assumption is generally justified for points 
along streams, railroads and roads, but in some cases may be 
in error. To get the elevation of the ground, at the house 
in the center of the map, Fig. 10, for example, we note that 

* See Minneapolis Quadrangle, U. S, G. S., for depression contours. 



30 WHAT A TOPOGRAPHIC MAP SHOWS 

the house is located at a distance of about to of the space from 
the 70 towards the 80 contour and if the ground rises uniformly 
a total of 10 feet in this distance it will rise to of 10 or 7 feet 
to the house which is therefore located on ground at a probable 
elevation of 77 feet. If the house had been shown half way 
between the contours the elevation would have been 75 feet, 
etc. On the other hand, it is possible that the ground between 
the 70 and 80 contours may behave as shown in Fig. 14a, 
that is, it may be located on a natural or artificial embank- 
ment in which case our estimate may be in error. It is obvious 
that the smaller the V. I. the smaller and consequently less im- 
portant will be any such "underfeature" and the more accurate 
any estimate of an elevation. As illustrated in Fig. 146 a 
5-foot interval would show the conditions much more closely. 
On the other hand, a map showing a small contour interval 
is expensive to make, as it requires very careful surveying, 
and the features brought out are relatively unimportant. 
The interval used also depends on the scale of the map. For 
landscape architecture an interval as small as 2 feet may 
be needed, 5 feet is commonly the smallest interval used 
and is found on many engineering maps, on maps drawn 
to a scale similar to the map in the folder in the back of the 
book, and on the detailed military maps of positions, trench 
systems, etc. The U. S. G. S. maps have in many cases a 
V. I. of 20 feet, which is smaller than is common in foreign 
maps. The smaller the V. I. the closer the contours will 
appear on the map. Such a map is easier to read than one 
with a larger interval. 

QUESTIONS 

Refer to the Hunterstown Sheet in folder in back cover. 

1. What is the V. I. on this map? 

2. What is meant by 707 on hill west of Goldenville? (C-8). 

3. Why is the same number, 647, on the two hills south of Guernsey? 

(A-8.) 

4. What is the elevation of the hill just east of Friends Grove S. H.? (A-7.) 

5. How much higher is Chestnut Hill (A-6) than Mt. Olivet S. H.? (A-7.) 

6. Which is higher, Plainview (B-5) or Biglerville (B-8)? How much? 

7. What is the elevation of water in Conewago Creek at Bridge S, H.? 

(B-6.) 



CONTOURS AND ELEVATIONS 31 

8. Where is the highest point on road from Biglerville (B-8) to Heidlers- 

burg (A-5)? 

9. Where is the lowest point on this road? What is its elevation? 

10. Where is the highest point on contour 540 between Boyd S. H. and 

Stock Farm? (E-8.) 

11. Is the contour marked 500, east of Stock Farm (E-8) correctly desig- 

nated? 

12. Which way does the water flow in the Conewago? 

13. When it is raining in Table Rock Station (C-8) in what direction does 

the water drain? 
Refer to Fig. 13. 

14. Which way does the Potomac flow? 

15. What is its elevation at Magnolia? 

16. What is the elevation of the highest point shown on Purslane Mountain? 

Art. 8. Relief— {Continued) 

In using contour maps it is very important that we learn 
to visualize the relief from the contours. That is we must 
be able to form a mental picture of the conformation of the 
ground represented when looking at contours, and not simply 
see a mass of curving lines. Various aids have been used to 
assist those who use contour, maps in forming a correct idea 
of the country represented. 

From a contour map we may construct a correct and 
accurate relief model of the ground represented. These models 
are made in different ways, but Fig. 15 shows an excellent 
but somewhat laborious method. Pieces of cardboard are 
cut out the exact size and shape of the contours shown in the 
contour map in Fig. 15a. When placed over each other in 
the proper position these form a solid made up of layers as 
shown in Fig. 15b. The thickness of the cardboard corresponds 
to the V. I. and, if the steps between these layers were filled 
with modeling clay so as to slope uniformly from the top 
edge of each layer to the top edge of the layer below, a true 
relief model would be formed. Time is seldom available 
to make relief models, but the layer idea is one which is often 
of assistance in forming a mental picture from the contours. 
It is the basis for at least two systems of contour rendering. 

Fig. 16 shows the so-called " layer system " for contour 
maps. The lower levels appear with a light tint which in- 



32 



WHAT A TOPOGRAPHIC MAP SHOWS 



creases with each succeeding layer and certainly assists in 
enabling us to picture the relative elevations and forms of 
the land. This system is common in many modern geogra- 




Fig. 15. — Construction of a Relief Model. 



phies and is used on the International Map of the World. 
On this map the layers are tinted on a modified prismatic 
scheme of colors, the ocean being blue, lowlands green, fol- 



CONTOUR AIDS 33 

lowea by yellow-brown tints of increasing strength with 
the highest peaks a deep magenta. The principal advantage 
of this system is that it allows instant comparison of the 
relative heights of separated sections of the country. For 
this reason it is particularly adapted to works on physical 
geography. As the number of color tints is limited and 
the process of printing expensive, it is not used on large- 
scale maps. Its principal disadvantage outside of cost is 




Fig. 16. — The Layer System for Contour Maps. 

that the tint is so deep for the high areas that it obscures 
the lettering and conventional signs. A sheet showing a 
portion of the top of a high plateau with low relief would 
be colored a deep brown or magenta all over, and no em- 
phasis would be possible to assist in picturing such relief as 
does exist.* 

The so-called "oroscopic " system, which is also based on 
the layer relief model idea, is illustrated in Fig. 17. The 
system in the form shown, which is taken from Morrow's 



* See some of the English maps of South Africa. 



34 WHAT A TOPOGRAPHIC MAP SHOWS 

" Contours and Maps," * is applicable only to relief maps as 
the deep base tint obscures conventional signs. The scheme 
is based on layers with horizontal lighting at 45 degrees from 
the upper left-hand corner. The edges of those layers which 
are toward the light are shown white, while the edges away 
from the light are drawn in black. The system is quite a 
striking one and can be worked out without a ground tint 
by using two colors for the contour lines themselves, say a 




Fig. 17. — Oroscopic System for Contour Maps. 



light pink and deep red. No maps are made in this way, but 
it is suggested as an advantageous modification of the type 
shown. 

Various methods of shading have also been used in connec- 
tion with contour maps and these probably offer one of the 
most satisfactory solutions of the problem. The Norwegian 
maps use shading which is sometimes referred to as based on 
a vertical lighting system. It is simply the substitution of 
shading for hachures. Thus on the English Ordnance maps, 

* See Appendix. 



CONTOUR AIDS 35 

where hachures and contours are used, the hachure may be 
said to be line shading based on the principle that the steeper 
the slope the darker the shading. On the Norwegian maps 
the shading is produced not by lines but by a gray tint of 
varying intensity. The effect is the same as if the ground 
were lighted from directly above, the steep slopes which would 
reflect little light being dark, the gentler slopes lightly shaded 
and flat mountain tops or plains left unshaded. 

The shading system used on the latest French maps is 
shown by the Frontispiece. It is based on a horizontal 45- 
degree lighting like the oroscopic maps but the intensity of 
the shading itself varies on the hachure plan as followed in 
the Norwegian maps. Each hill is treated by itself, the side 
which is in shade is shaded as noted above but the shadows 
cast by the hills are not shown. 

QUESTIONS 

1. Cut out pieces of cardboard and make a relief model of the contour map 

shown in Fig. 10. The shape of the contours can be taken off with 
tracing paper and transferred to cardboard with carbon paper. Use 
a square piece of cardboard for the base as shown in Fig. 15. 

2. Assuming the light to be horizontal and coming at 45° from the upper 

left-hand corner (similar to the rays of the sun in the late afternoon in 
the summer) shade the lower left-hand corner of Fig. 13. Follow the 
French system. Use a soft pencil and be careful to blend the tint 
from light to dark. Note that the line of division between light and 
shade runs through the points whew rays at 45° are tangent to the 
bends in the contours. • 



36 



WHAT A TOPOGRAPHIC MAP SHOWS 




Fig. 18.— 
Pointers. 



Art. 9. Direction 

It is very important that a map show the direction of 
north and when using a map in the field the person using 
it must know the direction of north on the 
ground. % 

The direction of north on the map is sometimes 
given by an arrow or pointer such as shown in 
Fig. 18. On old maps, these pointers were often 
very elaborate, and a complete drawing showing 
the notation of the mariner's compass (see Fig. 
21a) was frequently given. When parallels of 
latitude and longitude lines are shown (see Frontis- 
piece and Figs. 5 and 13) the latter are meridians 
or true north and south lines. When no other 
information is given it is usually safe to assume 
that the top of the map is north, and the right- 
and left-hand edges are north and south lines, as 
most maps are made in this way. 
The two lines shown in Fig. 18 are given because a compass 
is very commonly used in the field and the compass needle 
seldom points true north. The divergence between the two 
lines in the figure is the error in the pointing of the compass 
which is known as the declination. This error is due to the 
fact that the earth is a great magnet having a north and 
south pole just like a bar magnet, and these poles do not coin- 
cide with the geographic poles. The compass needle, point- 
ing as it does toward the magnetic pole, does not give a true 
north direction and furthermore the angle between the com- 
pass north and true north varies not only with the location 
of the observer, but also with time. For example, in the 
United States there is a curving line running in a southerly 
direction and passing through the Great Lakes region and 
leaving the coast in South Carolina, and at any point on 
which the declination is zero and the compass points true 
north. At points like New York, east of this line, the needle 
points west of north and at San Francisco, west of the "agonic 
line," it points east. To illustrate the variation with time 
the case of Paris, where long records are available, is inter- 



DIRECTION 37 

esting. In 1580 the declination was about 9|° east, and in 
1810 it was 22|° west. Hence declination must be known 
and allowed for in using a map, although when merely general 
directions are required such as northeast, southward, etc., 
it makes little difference. 

When using a map in the field to find one's way about, 
it is necessary (a) to know the direction of north and (6) to 
turn or "orient" the map so that its side edges will be north 
and south and the objects shown on the map will appear in 
the same direction as do the actual objects on the ground. 
For example, if you were in Goldenville (C-8) (see Hunters- 
town map in back of book), and wanted to go to Hunters- 
town (D-5) you would "orient" your map and take the road 
going in the same direction as the road to Hunterstown on 
the map, namely east. By keeping the map oriented you 
easily recognize the features shown as you go along the 
road. 

The direction of a north and south line, or meridian, 
on the ground can be determined in several ways. One of 
the easiest is by using a compass as noted above. Release 
the compass needle and hold the instrument horizontal so 
the needle can swing freely. Turn the box so that the north 
end of the needle reads the declination and a line through the 
zeros of the scale on the box will be true north. For example, 
if the declination is 10° W we turn the compass so the needle 
points 10° west of north and the north and south line of the 
compass markings will then be a true meridian. 

If a compass is not available a watch can be used. Hold 
the watch flat in the hand and with the hour hand pointing 
in the direction of the sun; a direction halfway between the 
hour hand and 12 is south. See Fig. 19. Remember that dur- 
ing the summer months all watches are one hour fast. 

At night the North Star, called also Polaris, can be easily 
found in the heavens and a line from the observer to this star 
is very close to true north. Polaris can be located in the sky 
by means of the two "pointers" of the Big Dipper as shown 
in Fig. 20. Of course the position of the Big Dipper is not 
always that shown in the figure, as all the stars appear to rotate 
about Polaris as a center, due to the rotation of the earth, 



38 WHAT A TOPOGRAPHIC MAP SHOWS 

and the Dipper will at times be above the Pole Star in a posi- 
tion that "would not hold water." Comparison of the com- 
pass with the north direction determined from Polaris is an 
excellent method of determining declination. 

Some people have an ability in sensing direction and 




J&x&r 



Fig. 19. — Determination of South with a Watch. 

when in the field, by day or night, always know the direction 
of north. This generally comes from a training in observing 
indications of direction such as the position of the sun, etc., that 
has become an almost unconscious habit. This sense of direc- 



*- 



. Polaris 

"*X or 

Nortli Star 



X 






Great Dipper / ^ x » S 



K 



/ Pointers 



Fig. 20.— The "Pointers" and the North Star. 

tion is entirely lacking in others and is a thing that children 
should early be taught to cultivate. Woodsmen note that 
moss prefers moisture and therefore grows best on the north 
side of trees, away from the sun. Certain plants such as the 
Compass Plant and Sow Thistle also arrange their leaves 



DIRECTION 



39 



or blossoms in certain directions and probably for similar 
easons. 

Directions are stated in several ways. Fig. 21a shows 
the scale in a compass box divided to give "the points of the 
compass." We can thus say that the direction of one point 
from another is north north east (N N E), etc., (6) shows the 




Fig. 21a. — Mariner's Compass. 



usual compass bearing graduation of the surveyor and we 
would speak of the same line as having a bearing of N 22|° E, 
meaning that it is 22f° from the North toward the East. 
Another method of stating the direction is shown in (c). 
This is known as the azimuth method and the circumference 
is divided from to 360°. The zero point, or zero azimuth, 



40 



WHAT A TOPOGRAPHIC MAP SHOWS 



in surveying, is usually taken as North, but in astronomical 
work azimuths are measured from the south point. Note 
that when directions are given by azimuth, measured from 
a zero direction agreed upon, it is necessary to state simply 
the angle. Thus for the line mentioned above the azimuth 




Fig. 21 b. — Surveyor's Compass Method. 



is simply 
three methods 



Mh > 



The following comparison illustrates the 



Mariner 

NNE 
SEby S 

wsw 

NW 



Surveyor 

N M\° E 
S 83$ ° E 
S 67J"° W 

N45° W 



Azimuth 

146f° 
147±° 
315° 



DIRECTION 



41 



To obtain the direction of a point B from a point A on a 
map place a piece of tracing paper over A and draw two lines 
on it showing both the north direction and the direction of 
B. This may then be placed over (a), (6), or (c) of Fig. 21 
and the direction read off. 




Fig. 21c. — Direction by Azimuth Method. 



QUESTIONS 

1. Express the following directions by the three different methods (Mariner's 

notation, Surveyor's bearings and azimuth), N W by W, S 45°W, 270°. 

Refer to the Hunterstown Sheet in back cover pr cket. 

2. State the general direction of Biglerville (B-8) ffOm Plainview (B-5) by 

simply inspecting the map. 

3. What is the direction of Table Rock (C-7) from Biglerville stated in the 

mariner's manner. 



42 WHAT A TOPOGRAPHIC MAP SHOWS 

4. Describe the direction of Benders Ch. (B-7) from the fork in the road at 

Table Rock by the surveyor's method. 

5. Assuming north for zero azimuth describe the direction of Table Rock 

S. H. (C-7) from the fork at Table Rock. 

6. Insert mariner's directions (using only the sixteen main points of the 

compass) in the following description of the road from Guernsey 
(A-8) to Table Rock (C-7) "From Guernsey go continuing past 

the first road coming in from and turn the next corner going 

At four corners take road running continue past road leading 

and at four corners pass straight through continuing and 

passing road coming in from to Table Rock." 

7. Write out similar description for the route from Plainview (B-5) to 

Hunterstown (D-5) passing Woodside S. H. (C-5.) 



Art. 10. Scale 

It has already been pointed out that maps are drawn so 
that the distance between any two points on the map always 
bears a certain relation to the corresponding distance on the 
ground. That is, one inch on the map may represent a mile 
on the ground and if we measure the distance between two 
towns on the map and find it is 2 \ inches, we then know that 
the actual distance on the ground is 2| miles. This state- 
ment of the relation between a distance on the map and the 
corresponding distance on the ground is known as the scale 
equivalent. There are two other ways of expressing the scale 
of a map, by stating the Representative Fraction and by 
giving a graphical or reading scale. The latter is discussed 
in Art. 11. In many cases the marginal information on the 
map states the scale in all three ways. 

The Representative Fraction (usually abbreviated to 
R. F.) of a map is simply the ratio between any distance on 
the map and the corresponding distance on the ground. Thus 
if one inch on the map represents a mile on the ground the 
R. F. of the map is 1: 63,360. This is true because one mile = 
5280 feet = 63,360 inches, and one inch on the map must 
represent one mile or 63,360 inches on the ground, hence the 
ratio between one unit on the map and the number of the same 
kind of units that it represents on the ground is 1 : 63,360. 
Stated in another way this means that the map is a picture of 
the ground reduced to one sixty-three thousand three hundred 



SCALE 43 

and sixtieth of its actual size. The R. F. being simply a ratio 
of size it is clear that it makes no difference what unit is used 
the ratio is the same. For example, we may write one inch 
on the map equals 63,360 inches on the ground or one foot 
or yard or meter equals 63,360 feet or yards or meters on 
the ground. 

Knowing the scale equivalent we can easily find the R. F. 
or knowing the R. F. we can find the scale equivalent. The 
operation involves only division and multiplication and is 
illustrated by the two following problems: 

The standard scale for U. S. Military maps of special 
features is 6 inches = 1 mile. What is the R. F.? We pro- 
ceed as follows : 

Six inches on the map equals one mile on the ground but 
one mile equals 63,360 inches, hence 

Six inches on the map equal 63,360 inches on the ground 
or one inch on the map equals 6 3 i 6 ° or 10,560 inches on the 
ground, hence the ratio between one unit on the map and the 
number of the same kind of units it represents on the ground, 
or the R. F., is 1: 10,560. Again: 

The Carte de France is drawn with an R. F. of 1 : 80,000. 
How many miles on the ground are represented by one inch 
on the map. 

If the R. F. is 1 : 80,000 we can write, 

One meter on the map equals 80,000 meters on the ground, 
or 

One yard on the map equals 80,000 yards on the ground, or 

One foot on the map equals 80,000 feet on the ground, 
but for our purpose it will be best to use the relation, 

One inch on the map equals 80,000 inches on the ground 
and since a mile is 63,360 inches we have, 

One inch on the map equals %%%%% or about If miles on 
the ground. 

It will be obvious from the above that while a map can have 
but one R. F., we can express its scale by innumerable scale 
equivalents. That is, we may say that one inch on the map 
equals 1| miles on the ground or one centimeter on the map 
equals 0.8 of a kilometer, or one inch equals 2 kilometers, or 
one centimenter equals half a mile, etc. These expressions 



44 WHAT A TOPOGRAPHIC MAP SHOWS 

are all simply different scale equivalents for a map having an 
R. F. of 1: 80,000. They are easily obtained if we know the 
relations of the different units employed. Thus a kilometer 
is 100,000 centimeters and since one centimeter on the map 
represents 80,000 centimeters on the ground, it must repre- 
sent 80,000 -f- 100,000 or 0.8 of a kilometer. Also since one 
mile equals 1.61 kilometers and one inch on the map repre- 
sents lj miles on the ground, it must represent 1^ times 1.61 
or practically 2 kilometers, etc. 

These problems in scale relations are, as stated above, 
simple arithmetic, but are often confusing to students. They 
must be thoroughly understood, however, as a proper under- 
standing of scale is of vital importance in using maps. The 
relation of the scale adopted for a map to the use to which 
the map is to be put, the size of the individual sheets of a 
map and convenience in handling, the amount of detail that 
is shown and the conventional signs, as well as to the method 
of showing relief and the V. I. of contour maps has been dis- 
cussed. (See Introduction and Arts. 2, 3, and 7.) The actual 
relation between the scale and contours of a map, and the 
ground represented cannot be taught from books. It comes 
only from actual practice in using a map in the field where it 
can be compared with the ground, and the student gradually 
acquires the ability to picture in his mind the ground rep- 
resented when looking at a map. 

The following tabulation gives some of the scales used on 
topographic maps: 

Kind of Map Scale Relief 

Landscape Design 1 in. = 25 or 50 ft. Contours. V. I. 2 or 3 

ft. 

Engineering Maps for roads, rail- 1 in. = 100 or 200 ft. Contours. V. I. 5 ft. 

roads, etc. 

U. S. Army fortification and other 12 in. = l mile Contours. V. I. 5 ft. 

detailed maps (1 in. =440 ft.) 

French maps of the Western Front 1 : 5000 Contours. V. I. 1 to 5 

(1 in. = 416fft.) meters 

U. S. Army Position Sketches and 6 in. = 1 mile. Contours. V. I. 10 ft. 

Maneuver maps also large scale (1 in. = 880 ft.) for former 
British Ordnance Map 

English Trench Maps and Artillery 1 : 10,000 Contours. V. I. 10 

Maps (1 in. = 833| ft.) meters 



SCALE CONVERSION 



45 



Kind of Map Scale Relief 

U. S. Army Road Maps or Sketches 3 in. = 1 mile Contours. V. I. 20 ft. 

(1 in. = 1760 ft.) 

German and Swiss large scale Govt. 1 : 25,000 Contours. V. I. 5 to 10 



Maps 
U. S. G. S. Maps 

(Important Areas) 
New French Maps 

English Ordnance Maps 

(Standard Edition) 
Carte de France 

German Standard Govt. Map 

U. S. G. S. 

(Unimportant Areas) 
U. S. G. S. 

(Plains) 
International Map of the World 



(1 in. = 2083Ht.) meters 
1:62,500 Contours. V. I. usually 

(lin. = 5208Ht.) 20 ft. 
1 : 50,000 Shaded Contours. V. I 

(1 in. = 4166f ft.) =10 meters 
1 in. = l mile Hachures with contours. 

V. I. 100 ft. 
Hachures 



(1 in. = 5280 ft.) 
1:80,000 

(1 in. = 6666| ft.) 
1: 100,000 

(1 in. = 8333^) 
1: 125,000 

1:250,000 

1: 1,000,000 



Hachures 

Contours. V. I. 10 to 
200 ft. 

Contours. V. I. 10 or 20 
ft. 

Contours with layer sys- 
tem V. I. variable 



QUESTIONS 

1. If the R. F. of a map is 1: 75,000, how many miles on the ground does 

one inch on the map represent? 

2. How many inches would be required on the above map to represent one 

mile on the ground? 

3. How many kilometers on the ground would one centimeter on the map 

represent? 

4. What would the answers to questions 1, 2 and 3 be if the R. F. was 

1:40,000? 

5. Suppose that the margin of a map has been torn off and you do not 

remember the scale. You do remember, however, that the distance 
between two towns is 2| miles and you find by measuring that this dis- 
tance on the map is 6| inches. What is the R. F.? 

6. Complete the following tabulation: 



R. F. 



1: 21,120 



1:62,500. 
1:20,000. 



Scale Equivalents 
or 1 in. - 1760 ft. or 3 in. = 1 m. 

or or 6 in. = 1 m. 

or or 12 in. = 1 m. 

or . or 

or or 



46 WHAT A TOPOGRAPHIC MAP SHOWS 

Art. 11. Scales — (Continued) 

Fig. 22 shows the reading or graphical scales printed on 
the bottom margin of those U. S. G. S. maps which are drawn 
with a R. F. of 1: 62,500. Scales of this kind may be made 
for any map and furnish the easiest means of measuring 
distances from the map in any unit. 

For example, the distance in a straight line between the 
railroad stations at Hansrote and Baird, Fig. 13, is required. 
The edge of a piece of paper is placed on the line between 
these points and the points are marked on the paper. This 
paper is then compared with the mile scale of Fig. 22. We 
place one mark opposite the zero of the scale and ilote that 
the other mark comes between the 1- and 2-mile divisions, 
thus indicating that the distance is between 1 and 2 miles. 
To read the distance to tenths of a mile we place one of the 
marks on the paper even with the 1-mile division of the scale 
and obtain the tenths, and if we wish to we can estimate the 
hundredths, by reading the closely graduated portion of the 
scale toward the left from the zero mark. The distance is 
read directly as a little over 1.8 miles or may be estimated 
as 1.82 miles. 

Graphical scales are made in this way with large divisions 
and an extra unit closely divided at the left end in order to 
make them simpler and make it unnecessary to divide the 
entire scale into the smaller units. The distance in kilometers 
can be read in the same manner from the kilometer scale of 
Fig. 22 and is 2.94 kilometers. Instead of using a piece of 
paper to compare distances with the scale a copy of the scale 
may be drawn on a piece of paper and the distances can be 
measured directly on the map. 

Distances in a straight line are required in taking from 
maps ranges for artillery fire, etc. More common problems, 
however, require distances between two points along a road. 
For example, what is the distance by road between Hansrote 
and Magnolia, Fig. 13? This is obtained by transferring 
to a strip of paper the successive short straight lengths which 
make up the total length. On this particular road there are 
a dozen or more of these lengths and on a curved line such as 



GRAPHICAL SCALES 



47 






^J 




(*—}(- 



V_ 



O 



— £ 



a 


c 


T3 ^J 


.2 




t- 






0) 


3 


— 


j 


t-H 




5b 


•4-> 

CO 

a 
o 
U 


— 


a 




1 


i 




■* 


l 





»< 




— 


d 


u 




£ 



48 WHAT A TOPOGRAPHIC MAP SHOWS 

a railroad, canal or stream we have to arbitrarily divide the 
total distance into a series of short lengths which we con- 
sider as straight. A special "measuring wheel" is made by 
instrument manufacturers for measuring curved distances, 
or a piece of thread may be placed along the line then straight- 
ened out and measured. Thread will often stretch, causing an 
error, unless the same pull is used on it when measuring and 
comparing. 

The construction of a graphical scale is best explained 
by a problem. Thus the mile scale of Fig. 22 is made as fol- 
lows: The R. F. of the map is 1:62,500 and we must find 
how many inches on the map represent one mile on the ground. 
When this value is found, in this case 1.01 inches on map 
equals 1 mile on the ground, the scale is constructed by lay- 
ing off successive lengths of 1.01 inches as shown in Fig. 23 
and dividing the end length into ten parts. Now the R. F. 
being 1:62,500 one inch on the map will represent 62,500 
inches on the ground. But one mile is 63,360 inches, hence 
a mile on the ground will be shown by 63,360 divided by 
62,500 or 1.01 inches on the map, giving the distance required 
for the major divisions of the scale, which are then laid off 
with a ruler or scale divided into inches and tenths such as is 
shown in Fig. 24 (an engineer's scale). The sub-division of 
the left-end length of the scale into ten parts can be done by 
trial or by the construction shown in Fig. 23. Any line AB 
is drawn ten units in length and these units marked as at a, 
b, c, etc. B is connected with the zero mark. Lines are 
then drawn parallel to the B-zero-line through each of the points 
a, b, c, etc., thus dividing the length A to zero into ten equal 
parts. 

The accuracy of distances scaled from maps depends upon 
several things. First the care with which the distances are 
measured and compared with the scale. For accurate work 
a pair of dividers should be used. Secondly, points shown on 
the map may or may not be shown in their exact location due 
to errors in making the map. Great accuracy in locating all 
points shown on a map is costly and it is customary to show 
some unimportant features only in their approximate posi- 
tions. For example, all survey points, such as triangulation 



GRAPHICAL SCALES 49 

stations, are very accurately located and drawn. Roads are 
also usually carefully surveyed and drawn. Hence distances 
between points on roads are quite accurate, probably at 
least to 1 or 2%, while in scaling distances between survey 
points the error is all in the scaling, not in the map. Other 
points are subject to more or less error, and a method followed 
in obtaining accurate distances is to measure on the map the 
distance between two points thought to be well located and 
near the required points. Then measure on the ground the 
actual distance between the required points and the points 
/selected on the map and add to or subtract from the dis- 
tance scaled from the map the distances measured on the 
ground. 

The accuracy of positions shown on the map also depends 
on the condition of the map. The paper on which the map 
is printed expands, or contracts, with climatic changes and 
due to the process of printing. For this reason it is always 
best to use the reading scale printed on the sheet itself in 
measuring distances. In highly accurate artillery work the 
map is cut up into small sections along the latitude and longi- 
tude lines and these sections are then pasted in their proper 
position on a zinc sheet on which the latitude and longitude 
lines have previously been carefully drawn. 

Another feature which influences the accuracy of both 
direction and distance in long distances is the projection 
(see Art. 2) of the map. This feature is not important except 
in very accurate work. 

QUESTIONS 

1. Construct a graphical or reading scale having main divisions of 1000 

yards' value and an end portion graduated to 100 yards for use with a 
map drawn with a R. F. of 1:20,000. Give all calculations in neat 
form and construct the scale by the method of Fig. 23, using the 
engineer' scale of inches and decimals shown in Fig. 24. 

Refer to Hunterstown Sheet in back cover. 

2. What is the distance in miles across this map from east to west? 

3. What is the distance from Biglerville (B-8) to Goldenville (C-8)? 

(a) In a straight line? (6) By road? (c) By railroad? 

4. What is the distance from Bridge S. H. to Herschey Mill (B-6) by farm 

roads? 



50 



WHAT A TOPOGRAPHIC MAP SHOWS 



5. Enemy has artillery on Chestnut Hill (A-6). Can they shoot to Plain- 

view? (B-5.)* 

6. Enemy has infantry on Chestnut Hill. Can they shoot to Plainview?* 

7. How far does Biglerville (B-8) extend along the road from east to west 

in hundreds of yards? 

8. What are the dimensions in yards of the orchard southwest of Hunters- 

town? (D-5.) 

9. Assuming that the trees are 5 yards apart, about how many are there in 

the orchard? Does each circle represent a tree? 

* The classification of ranges is given as follows in Field Service Regulations. 
Appendix 7, p. 205. 



Range. 


Rifle, Yards. 


Field Artillery, 
Yards. 


Heavy Artillery, 
Yards. 


Distant 

Long 


Over 2000 
2000 to 1200 
1200 to 600 

Under 600 


Over 4500 
4500 to 3500 
3500 to 2500 

Under 2500 


Over 6500 
6500 to 4000 


Effective 

Close 


4000 to 2500 
Under 2500 







CHAPTER II 

HOW TO GET CERTAIN INFORMATION 
FROM A MAP 

Art. 12. Sections and Profiles 

Sections and profiles are easily constructed from con- 
tour maps and reduce the information shown on such maps 




Fig. 25. — Section and Profile. 

to a form which is often more convenient and better for 
certain kinds of work than the map itself. In using maps 
time is not always available to construct profiles, but the 

51 



52 



HOW TO GET CERTAIN INFORMATION 



ability to picture in the mind the approximate form and 
characteristics of a section or profile along some line on the 
map is very important. 

Fig. 25 illustrates the terms, section and profile. Thus 
Fig. 25a shows a model of a rounded island similar to Fig. 
12a. Imagine a vertical plane, AB, to cut through the model 
on the line abc like a large knife. When the right-hand portion 
of the model is removed it would look like Fig. 25b. If the 




1000 



900 



Profile 




1000 



900 



,800 



Fig. 26. — Construction of a Profile. 



model is now turned around so that the plane AB is directly 
facing the observer, Fig. 25c shows the result. The portion 
of this figure marked by line shading (cross-hatched) is a 
section of the model on a plane through A and C and the top 
boundary of the section, which is shown by a heavy line 
lettered abc in Fig. 25c, is a profile across the model on the 
line ac. A profile is therefore a curving line which shows the 
ups and downs of the surface along a line on the model or 



SECTION AND PROFILES 53 

in reduced scale, a line on the ground represented by the 
model. Sections are usually drawn showing the intersection 
of the ground and an imaginary vertical plane as is illustrated 
in Fig. 25, but profiles may be drawn for any line on a model 
or the ground, curved or straight, and it is only when the 
line is straight that the profile represents the intersection of 
a vertical plane with the surface of the ground and is therefore 
the top boundary of a section. 

For example, Fig. 26a shows a contour map. A profile 
may be drawn of the road between A and B. This profile 
will show the ups and downs of a line on the ground which 
follows the center of the road from A to B, as is shown by Fig. 
266. It is made as follows: By an examination of Fig. 26a 
it is noted that the lowest point on the road is at the bridge 
and is just below 850, while the highest point is B which is 
over 1000 feet. A horizontal line is drawn on a piece of paper 
to represent an elevation of 800 feet and is marked 800. Other 
horizontal lines are drawn above this line at a convenient 
spacing to represent 850, 900, 950, and 1000 feet. A point 
is selected at the left end of the paper to represent the point 
A on the map. The elevation of A is seen, from the map, 
to be 850 feet and it is plotted at A on the profile Fig. 266. 
The distance Ab, be, cd, de, ef, fg, gh, and hB are measured 
from the map along the center of the road and laid off on the 
profile as A'V , b'c' ', etc. The point 6 on the map is seen to 
be 900 feet elevation so 6 on the profile is plotted directly 
above b' at 900 feet and similarly for the other points. These 
points A, 6, c, etc., on the profile are then connected by a 
smooth, curving line which thus gives the ups and downs 
of the road between A and B as required. Note that we 
must estimate the height of the road between 6 and c and 
at such points as the bridge in order to draw the profile prop- 
erly between the plotted points 6 and c and d and e. 

Special paper, known as profile paper, can be obtained 
for plotting profiles. The steps in the process, as described 
.above, are 1, Selection of a base line, or bottom line, for the 
profile which will be lower than the lowest point on the profile 
so that the profile will not run below the lower edge of the 
profile paper. It is of course unnecessary and a waste of 






54 HOW TO GET CERTAIN INFORMATION 

paper to make the bottom of the paper datum or zero level. 
2, The horizontal scale of the profile is generally made the 
same as the map, but a vertical scale must be assumed. Often 
the most convenient plan is to draw lines on the paper, or in 
using profile paper consider the space between two horizontal 
lines, as representing the contour interval. This will, in most 
cases, exaggerate the vertical scale. That is, one inch meas- 
ured vertically will represent a smaller number of feet than 
one inch measured horizontally. Such a procedure does not 
produce a "natural" profile, but it does result in accentuating 
the hills and slopes which does not detract from the useful- 
ness of the profile and makes it easier to work with. Ordi- 
narily the ratio between the horizontal and vertical scales 
is made from 5 to 10, as this has been found to give a suitable 
profile. Thus the map shown in Fig. 26a may be drawn to 
a scale of three inches equals one mile and the horizontal 
scale of the profile, Fig. 266, will be the same, namely, 1760 
feet to one inch, Now the greatest difference in elevation 
on this profile is about 200 feet, hence, if the vertical scale 
was made the same as the horizontal, the point B on the 
profile would be shown about | of an inch (1760-^200) above 
A. This would be the natural profile, but the exaggerated 
profile, drawn so that one inch equals 300 feet or six times 
greater than the horizontal scale, shows the ups and downs 
of the ground much more clearly and is quite as useful. 

The use of profiles in connection with problems in slopes 
and visibility is the subject of the next four articles. 

QUESTIONS 

1. Draw a profile of the line of the divide of Fig. 10. Make the horizontal 

scale the same as that of the figure, which can be taken as 12 inches = 
1 mile and the vertical scale 1 inch =50 feet. 

2. What is the*ratio of exaggeration in question 1? 

3. Draw a section directly across Fig. 13 on the latitude line shown. Note 

that only the hundred-foot contours need be plotted except at the 
tops of hills and bottom of valleys where the elevations should be 
estimated. Use a horizontal scale of the same as the map and a suitable 
vertical scale. 

4. Draw a profile of the road from Hem to Fienvillers on Fig. 7. This is a 

hachure map and the profile will necessarily be less accurate than that 



SLOPES 



55 



obtained from a contour map, but at the 
same time can be made with considerable 
accuracy by careful study and estimation. 

Note. The horizontal and vertical scales must 
always be given as part of the title of a profile. 

Art. 13. Slopes 

One of the most important things 
to determine from a topographic map 
is the slope or grade of the hills, roads, 
railroads, etc. It is necessary to under- 
stand how slopes are described before 
discussing the various ways in which a 
knowledge of slopes is useful. 

Fig. 27 illustrates by cross-sections 
the three forms in which slopes are 
stated, namely: a, by giving the slope 
angle, b, by the slope fraction, and c, in 
per cent. 

The slope angle is shown in Fig. 
27a, and is the angle between the slop- 
ing surface and the horizontal. We 
may therefore speak of a slope of 3°, 
meaning an angle BAC of 3°. 

The slope fraction or ratio is the 
ratio between the rise, or amount we 
go up, and the horizontal distance, or 
base, which corresponds to this rise. 
Fig. 276. For example, the horizontal 
distance between two contours on a 
map having a V. I. of 10 feet may be 
scaled from the map and found to be 
100 feet. If the ground surface slopes 
uniformly between these two contours 
its slope is 10 in 100 or to which is the 
slope fraction, the rise being 10 for a 
base, or horizontal distance, of 100. 
Engineers frequently speak of slopes of 
embankments as 1 in 1| or 1 on 1| for 




i £ 



| 09 



~ t-T 



05 Q, 



o 
w 






J 



w| 



56 HOW TO GET CERTAIN INFORMATION 

example. This is a common slope for railroad embankments 
and the statement means that the rise is 1 foot or yard for a 
base of 1^ feet or yards, or corresponding unit. In other words 
instead of stating the slope fraction, which in this case is 1 4- 1| 
or f, they state the rise and base. 

When giving the slope of a road or railroad it is quite com- 
mon to give the grade in per cent. That is give the units rise 
for a base of 100 units. Thus in the case of the two contours 
mentioned above the rise is 10 feet in 100 feet, hence th 
grade is 10%. See Fig. 27c. 

It is obviously quite easy to change from a slope fraction 
to per cent or vice versa. Thus a slope fraction of £ means 
a rise of 1 for a base of 6 and if the base was 100 the rise would 
be 100^6 or 16f, hence the grade is 16f%. Or the slope 



: 



i 

k AC =57.3 Units- 



Angle =r 



""t-^l'Uriit 



Fig. 28.— Relations for 1° Angle. 

fraction for a grade of 5% must be £s, since a 5% grade means 
a rise of 5 for a base of 100 or 1 for a base of 20. 

It is also easily possible to find the slope fraction corre- 
sponding to any angle of slope or vice versa. This may be 
done with sufficient accuracy for many problems, if the slope 
is not too high, by the relation shown in Fig. 28. In this 
figure two lines have been drawn, making an angle of 1° and 
a vertical BC has been drawn perpendicular to the base AC. 
If BC and AC are measured, it will be found that AC is almost 
60 (57.3 to be more exact) times as long as BC. That is the 
slope ratio is 1 in 57.3 for a slope angle 1°. This relation is 
very convenient and a student should remember that: 

A slope of 1° means a rise of 1 foot in 57.3 feet, or 

A slope of 1° means a rise of 1 foot in 688 inches. 

Now it is also approximately true as shown in Fig. 29 
that a 2° slope will give a rise of 2 units in a base of 57.3 units, 
a 3° angle a rise of 3, etc. Hence we may write 

Slope angle in degrees 

Slope ratio = 

r 57.3 



SLOPES 



57 



from which it follows that, 

Slope angle in degrees equals 57.3 times the slope ratio. 

It is quite obvious that the steeper a slope is the more 
difficult it will be for horses to pull wagons or artillery up or 
for troops to charge. The following table, taken from Field 



2 Unit? 




-57.3 Units >J 

Fig. 29. — Relation of Slope Angle and Rise. 

Service Regulations, Appendix 7, p. 226, shows the greatest 
slopes that are practical for certain operations. 





Slope. 




Operation. 








Degrees. 


Fraction. 


Per Cent. 




1 


i 

60 


2 


Maximum for good railroads 


3 


1 
20 


5 


Maximum for first-class roads 


5 


1 

12 


8 


Practical for all arms. Somewhat difficult for cavalry to 
charge descending 


6 


1 
10 


10 


Maximum for cavalry charge in mass ascending. Infan- 
try in close order descends with some difficulty. 


7 


1 


12 


Cavalry can descend at a trot 


8 


1 
7 


14 


Not practicable for heavily loaded vehicles 


n 


1 
6 


16 


Field Artillery can no longer maneuver 


15 


1 


25 


Maximum up to which all arms can move 


18| 


1 


33 


Light vehicles can ascend 


26 


1 
2 


50 


Individuals or mules can ascend or descend 


45 


1 
1 


100 


Foot troops can ascend or descend aided by hands 



Note that in this table the slope has been expressed as 
an angle with the approximate equivalents for the ratio and 
per cent. In studying the table it is also interesting to note 
that infantry or cavalry can maneuver ascending a steeper 
slope than they can negotiate descending. The slope figure 
given for railroads is often exceeded on small lines where 
grades of as high as 4% are sometimes found, while a large 
trunk line would not have a grade of over 1% at the most. 
The slope given for roads is also frequently exceeded and grades 
as high as 7% will be found on some macadamized roads and 
country roads will sometimes have grades of 10% and over. 
No figure is given in this table for motor trucks, but they can 



58 



HOW TO GET CERTAIN INFORMATION 



safely negotiate any grade that is suitable for wagons. Indeed 
the chief difficulty encountered in motor transport in many 
sections of country is in connection with bridges and culverts. 
Small plank culverts very often crush through under the heavy 
wheel loads of trucks. The narrow width of many country 
roads and the high crown given to the surface also frequently 
causes a heavily loaded wagon or truck to skid off into the 
gutter, particularly in wet weather. It might be possible in 
many cases where the steep grade on a road is short, to double 
up the teams and take one wagon up at a time. It is almost 
always advisable, however, to take a longer but easier route 



o o o © 

lO «D C-~ CO 

to to tO o 



B 











Contours VI 10 Ft. 










B 


^B 
Vertical Angle A to B ^X 


^> — Tip 








1 
|50 

I 


^^\^ - " ' /\ Slope Angle 

^J^r^C — CtpB 

Slope Angle A to C 














(a) 


One 


Slope ' 




(b) Two Slopes 



Fig. 30. — Contours and Slopes. 



in moving a wagon train to avoid the delay that this pro- 
cedure occasions. 

Slopes may be obtained from contour maps as was indi- 
cated in discussing the slope ratio above. This may be done 
by direct measurement and computation from the map or 
by using a Map Distance Scale, which is described in Art. 
14. To compute the slope the V. I. of the map must be known 
and the distance on the ground between the contours, which 
gives the slope, must be scaled from the map by using a read- 
ing scale or by measuring it in inches and allowing for the 
R. F. Thus if the V. I. is 20 feet and two contours are 400 
yards apart the slope indicated is 1 in 60 or about 1° or 1.75%. 

Note that the steepest portions of a road or slope are the 



CONTOURS AND SLOPES 59 

critical places in considering any operation, hence we first 
examine the map to find where the contours are most closely 
spaced. If several contours are evenly spaced a more accurate 
computation can be made by dividing the sum of the inter- 
vals by the distance between the outside contours. Thus in 
Fig. 30a it is more accurate to divide the sum of the intervals 
A to B, or 50 feet, by the horizontal distance A to B than to 
divide 10 feet by the horizontal distance A to C. The result 
should be the same, as the even spacing indicates a uniform 
slope, but the larger horizontal distance A to B can be scaled 
with no more error and hence greater accuracy than A to C. 
Note that this can only be done where the spacing of the 
contour is uniform. Thus Fig. 306, where the spacing is not 
uniform, shows not one slope, but two, and if the distance A 
to B is used the angle obtained is what is known as the vertical 
angle between A and B and is not the slope angle, as there are 
two slope angles, that from A to C and that from C to B. 

QUESTIONS 

1. A slope is 3| degrees. What is the slope fraction? What is the slope in 

per cent? 

2. A construction railroad has a grade of 4%. What is the slope angle? 

The slope fraction? 

3. A railroad embankment usually has a slope of 1 on lj. What is the 

approximate angle of slope? 
Refer to Hunter stown Map. 

4. Are there any steep slopes on the road from Biglerville (B-5) to Gainer 

(B-8)? How steep? Answer in grade per cent. 

5. Are there any steep slopes on the road from Plain view (B-5) to Heidlers- 

burg (A-5)? How steep? Answer in grade fraction. 

6. What is the steepest slope in degrees on the road from Bridge S. H. to 

Hill 712? (B-6.) Answer in slope angle. 

7. Determine the per cent grade of the steepest slope on the portion of 

Chestnut Hill shown on this map (A-6). 

Art. 14. Slopes — {Continued) 

It is the practice to give at the bottom of the U. S. Army- 
War Game maps, in addition to the usual reading scale, a 
scale showing what are called map distances, or distances 
between consecutive contours on the map for various slopes. 
A scale of this kind is shown in Fig. 31 and is usually referred 



60 HOW TO GET CERTAIN INFORMATION 

to as a M. D. (map distance) scale, although slope scale is a 
better term. The slope scale furnishes a very rapid and con- 
venient method of getting the slope between any two consecu- 
tive contours on the map. Thus if the distance between two 
consecutive contours is laid off on a strip of paper and when 
compared with scale just equals the distance from A to B, 
then the slope is f °, if it equals BC the slope is 1°, etc. Or a 
copy of the scale may be made on a piece of paper and this 
copy applied directly to the map, the slope being found by 
moving the scale until two divisions on it coincide with the 
two consecutive contours on the map the slope between which 
is desired. In many cases no divisions on the scale will exactly 
fit the contours. For example, two contours may be closer 
together than the division from A to B in Fig. 31, but not as 
close as B to C. This means that the slope is between § and 1°. 
It will be noticed that the divisions on this scale bear a 
very simple relation to each other. Thus the length AB is 

A B C D E 

Fig. 31.— Slope Scale. 

twice the length BC, CD is half BC, DE is a third of BC, 
etc. When we remember that a slope of |° becomes (approxi- 
mately) a slope of 1° if the rise is kept the same and the base 
is reduced to one-half the reason for this relationship is clear. 
It will also be true that if the distance between the outer two 
of four consecutive evenly spaced contours just coincides 
with the distance between the 1° divisions (BC in Fig. 31) 
then the slope is ^ of 1° or |°. This furnishes a method of 
scaling slopes so that a scale with only even divisions like those 
shown in Fig. 31 may be used to get practically any slope. 

Most maps do not have a slope scale printed on them, and 
if we desire to measure many slopes it is advisable to make 
a slope scale. The construction of a slope scale is quite simple 
and is best illustrated by an example. 

Suppose a slope scale is required for a map drawn with 
a R. F. of 1 : 21,120 and having contours with a V. I. of 20 
feet. We compute the distance required on the map between 



SLOPE SCALES 61 

two consecutive contours for a slope of 1° and then divide 
this value to obtain the distances for other slopes as indicated 
above. Thus if the V. I. is 20 feet the slope of the ground 
between two consecutive contours will be 1° if these contours 
are 20 times 57.3 (see Art. 13) or 1146 feet apart, that is if 
the rise is 20 in 1146 or 1 in 57.3. Now 1146 feet is 13,752 
inches and, if the R. F. is 1: 21,120, this distance would be 
shown on the map as 13,752-=- 21,120 or 0.65 of an inch. Hence 
the map distance for 1° is 0.65 inch and we lay off BC in Fig. 
32 = 0.65 inch using for this purpose an engineer's, or decimal 
scale (see Fig. 24). The scale is then completed by laying 

A U° B 1° C 2° 3° , 4° 5 o G o 7 o 8 o A0° 

u 1 1 — 1 111 1M 1 1 

; j i i „i i i i i i i i 

K— 1.30- ** 0.65- -^.32^.22^7^^4**1*4^ 

0.11 0.09" \ 08 » 
Fig. 32. — Construction of Slope Scale. 

off AB just twice BC, or 1.30 inches, CD half as long as BC 
or 0.37 inch, etc., as illustrated in the figure. 

We may write out the steps in this computation in the 
form of an equation as follows: 

_57.3 times V. I. in feet times 12 times R. F. 
Angle of slope in degrees 

where MD stands for the distance on the map in inches be- 
tween two consecutive contours for any angle of slope. 

It will be noted in connection with the U. S. Army maps 
that the V. I. and R. F. are so related that one slope scale will 
serve for all of these maps. For example, if the scale of the 
map is 12 inches = 1 mile, the V. I. used is 5 feet, if it is 6 inches 
= 1 mile, the V. I. used is twice as large, or 10 feet, etc., hence 
the distance on either of these maps for a certain slope will 
be the same. These R. F.'s and V. I.'s are therefore called 
normal scales. The fact that the spacing of the contours always 
shows the same slopes means that the ability to picture in 
the mind the size and slopes of hills from one of these maps 
holds also for the others, whereas with the usual maps of 



62 



HOW TO GET CERTAIN INFORMATION 



different scale and V. I. each map must be studied and visual- 
ized by itself. 

QUESTIONS 

1. The scale for some of the English Trench Maps used in France was 

1 : 20,000. The contour interval was 10 meters. Construct a slope scale 
for slopes of §, f , 1, 2, 3, 4, and 5 degrees. 
Note. 1 Meter equals 3.28 feet or about 39^ inches. 
Using the Hunterstown sheet, the M.D. or slope scale printed thereon and 
the table of practical slopes given in Art. 13, answer the following questions: 

2. Could wagons go straight up Chestnut Hill from the south? How steep 

is the slope? 

3. Could cavalry charge freely east of Table Rock Station? (C-8). 

4. Could artillery move on every slope on this map? If not, tell where not. 

5. Could infantry move on every slope on this map? Could it charge? 

If not, tell where not. 



Art. 15. Intervisibility of Points 

The problem of determining whether one point on the 
ground is visible from another point, that is, whether or not 

Topographic Crest 
B 




{a) (b) 

Fig. 33. — Topographic and Military Crests. 

r our "line of sight" is cut off by some intervening hill, can be 
readily determined from a contour map and is of great impor- 
tance in military operations. For example, in selecting signal 
stations, in determining whether a certain road is visible 
from any enemy position, etc. The method used in working 
out these questions also leads to the problem of visibility of 
areas, discussed in the next article, is basic in making a land- 
scape sketch from a map, and is frequently used as an aid in 
the recognition of objects in the field from a map. 

One of the simplest problems in visibility is illustrated in 
Fig. 33. An observer at the topographic crest of the hill, 



INTERVISIBILITY 



shown in profile in Figure a, would not be able to see to the 
bottom of the hill, as his line of sight would be cut off by the 
brow of the hill at B. All the ground between B and C is 
therefore out of sight and is "dead ground." In locating a 
trench on a hill like this, it would be located as shown in 
Fig. 336 at the "military crest," so that an attacking party 
would be in full view from the trench and could not take 
advantage of the cover offered by dead ground, as would occur 
if the trench was placed at the topographic crest. Note the 
characteristic contour spacing for a hill of this kind shown 
in Fig. 34a. It is obvious that the trench must follow closely 
the line of the 550 contour. When the contours are spaced 
as in Fig. 346 the topographic and military crest coincide. 




o © 



o ooo o© o 
CO co to CO cot- t- 




Fig. 34. — Location of Crest as shown by Contours. 

The problem of locating the military crest of a ridge does not, 
therefore, require drawing a profile and it can be easily traced 
on a contour map, provided the student understands contours 
and is able to picture in his mind the profile of a slope by study- 
ing the contours. 

In connection with the problem of intervisibility of two 
points (a low point A and higher point B) when there is an 
intervening hill or obstacle in the way it is clear, 

1. That we can see from A to B if the height, or elevation, 
of C is not greater than that of A, the lower of the two points. 

2. If C is as high or higher than B then A and B are not 
intervisible. 

3. If C is intermediate in height between A and B further 
study is necessary to answer the question. 

For example, we are standing at the corner of the roads 



64 HOW TO GET CERTAIN INFORMATION 

near D. Wirt's farm (C-6) on the Hunterstown sheet. Can we 
see the top of Chestnut Hill (A-6)? Our elevation at Wirt's 
is 552 plus our height, say 558 feet. If there is no hill between 
Wirt's and Chestnut Hill higher than 558 we know that we 
can see to the top of Chestnut Hill, as it is higher than 558 
(shown as 931). Upon examining the map we; find that there 
is a hill^between having an elevation of 712, hence further 
study is necessary to answer the question. 

Fig. 35 shows a profile drawn on the line from Wirt's to 
Chestnut Hill. If we draw a line of sight on the profile from 
A just touching the top of C we find that it is high above B, 
hence the obstacle C effectively blocks out our view of Chest- 
nut Hill. It is immediately obvious that it was unnecessary 



Chestnut Hill 
931 

B 




Fig. 35. — Intervisibility. 

for us to plot a complete profile to answer this question. All 
we need to plot are A, B, and C. 

Instead of answering the problem by a graphical solution 
as above we can easily work it out mathematically. Thus we 
find that the distance from Wirt's (A) to Hill 712 (C) is one 
mile, while that from Wirt's to Chestnut Hill is 3| miles on 
the map. Now a line of sight from Wirt's just passing over 
Hill 712 will rise 712-558 or 154 feet, or a rise of 154 feet in 
one mile. Hence at a distance of S- 2 miles the line of sight will 
rise in proportion 154x3j-=-l, or 540 feet, and its elevation 
will be 558+540, or 1098 feet, which is higher than Chestnut 
Hill (931) and the hill is therefore invisible. This method is 
illustrated in Fig. 36. Note that the distances A to C and A 
to B need not be scaled in miles, but can be measured in any 
convenient unit. Indeed this problem can be solved mentally 
with sufficient accuracy to answer the question. 



VISIBILITY PROBLEMS 



65 



It is obvious that Chestnut Hill would have been visible 
if the line of sight at B had been 931 feet or lower. Another 
problem which is solved in a similar manner is to determine 
the height necessary for a tower at Wirt's in order that we 
may see Chestnut Hill. Graphically we simply draw a line 
of sight back from B just touching C and find that it comes 




.El. 712 



^31.;558 



Fig. 36. — Intervisibility Computation. 

at D about 60 or 70 feet above A, giving the required height 
as shown by the dotted line in Fig. 35. Mathematically, we 
know that this line of sight must have a slope of 931 — 712, 
or 219 feet in 2 \ miles (the distance from Hill 712 to Chest- 
nut Hill), hence between Hill 712 and Wirt's it will drop 
219Xl-^2f, or 88 feet and its elevation at Wirt's would be 



Horizontal Line - Tangent to levelline at A 
-LMile.-V 2 Miles 3 Miles 1 Miles 




c «rv ature 

Fig. 37. — Error Due to Curvature of the Earth. 



712 — 88, or 624 feet. Hence the tower at Wirt's would have 
to be at least 624-558, or 66 feet high. 

Note that the map used in the above problem shows trees 
and the orchard on the north slope of Hill 712 may interfere 
with our view. Also the trees on Chestnut Hill might inter- 
fere with a view from there toward Wirt's. On maps where 



66 HOW TO GET CERTAIN INFORMATION 



& 






trees are not shown an allowance of 40 or 50 feet or more 
would have to be made for them. 

It is also true that the curvature of the earth would amount 
to enough in long sights to make allowance for it necessary. 
This is illustrated in Fig. 37 where AB is a horizontal line at 
A, that is, it is tangent to the earth's surface at A, and AC 
is a level line, that is, is parallel to the earth's surface, and it 
is from such a line that heights shown on maps are measured. 
Now the difference between these two lines is 8 inches in a 
distance of one mile and increases as the square of the distance 
(approximately). Hence an object four miles away due to 
curvature would appear to be 10§ feet ( = 8x4x4-7-12) 
lower than it is. 

QUESTIONS 

1. Could you see Hunterstown (D-5) from top of hill 574 (C-6)? 

2. Could the enemy see you at Herman (C-7) from Biglerville (B-8) ? 

3. Could they see you at Goodintent S.H.? (D-7.) 

4. You have been on lookout for three hours on hill 712 (B-6). A farmer 

tells you that he just came from Center Mills (A-7) to Bridge S. H. 
(B-6) with a hostile regiment. Is it true? 

5. You are in Hunterstown (D-5) for a half -hour stop and expect enemy 

from west. Where do you put lookouts? 

6. You are marching southwest from Plainview (B-5). Where do you send 

patrols if enemy is expected from west? 

7. Do you send a separate patrol to each hill? 

8. Enemy has artillery at Biglerville (B-8) and holds line of Conewago. 

You are told to take a company from Goldenville (D-8) to Texas 
(C-8). Describe route? 

9. You are at cross-road 600 (B-7). You are ordered to go in daylight 

to Center Mills (A-7) without being seen. Describe route? 

Art. 16. Visibility of Areas 

Fig. 38 is identical with Fig. 13 except that a portion of 
the upper part of the map has been shaded. This shaded 
portion is ground that is not visible to an observer stationed 
at the point A, that is, it is dead ground. It requires time and 
patience to work out on a map and show in this way the areas 
visible or not visible from a given point, but such a problem 
is an excellent study in contours and the visualization of the 




FIG. 38. SHOWING AREA VISIBLE FROM POINT OF OBSERVATION AT A. 



VISIBILITY OF AREAS 



67 



relief. The result is of value in military work in planning 
attacks or troop movements, so as to take advantage of cover 
and in such work as locating observation stations, etc. In 
artillery work it is desirable to work out on a map in this way 
the dead ground in front of an artillery position and place 
the various batteries so as to effectively cover the entire area. 
In the case of artillery fire it is necessary to allow for the 
curving trajectory of the projectile and large areas that 
are not visible to the eye can of course be reached by the 
guns. 

The problem of working out the visible area is simply the 
application of the principles of Art. 15 to an area rather than 




Fig. 39. — Profile showing Lines of Visibility. 



one line. Thus from the map (Fig. 38) we can construct a 
profile on one of the radiating lines, such as AB, which have 
been drawn from the position of the observer at A. Fig. 39 
shows this profile. From the observation point A, which is 
at elevation 930, draw the lines of sight just over the inter- 
vening hills 1, 3, 5, and 7. It is obvious that the ground be- 
tween the points 1 and 2, 3 and 4, 5 and 6, and 7 and 8, is 
invisible, and this has been indicated by drawing the line XY 
at the bottom of the profile and marking the invisible portions 
with a heavy line. This marking is now transferred back to 
the map, Fig. 38, giving the line AB with invisible portions 
indicated by heavy ruling. Profiles are constructed and the 



68 HOW TO GET CERTAIN INFORMATION 

invisible portions of the other radiating lines AC, AD, AE, 
etc., are shown on the map. Indeed it would be advisable to 
work out even more lines than those shown. It is not always 
necessary to construct profiles in order to work out the visible 
portions, as this can be done quite easily mathematically. 
For example, on the line AD it is obvious that our line of sight 
will be cut off by the crest of the hill at L, just across the 
Potomac from the observer. The next hill which may, or may 
not, be visible is about an equal distance from the first hill 
across the next bend in the river at M. N ow the crest of the 
first hill (L) is at about elevation 830, hence the line of sight 
from the observer passing just over this hill will drop from 930 
to 830 or 100 feet in this distance, and in the approximately 
equal distance to the second hill (M) will drop about 100 more 
and hence will be at about 830-100 or 730 at M. Now this 
hill rises to over 820 feet, hence it will be visible from elevation 
730 to the crest as shown. This same method can be followed 
for the next hill, N, in which case the line of sight is con- 
trolled by the elevation of the observer (930) and the eleva- 
tion of the crest of the hill, M. 

Having indicated the visible and invisible portions of the 
ground on a number of these selected lines radiating from the 
observer, it is next necessary to connect up by eye the corre- 
sponding points on the different lines and thus outline the 
boundaries of the dead ground. This requires considerable 
thought and skill, and the following points will be helpful: 

1. Hillsides facing toward the observer, and not cut off 
entirely from view by an intervening hill or ridge, will be 
visible from their crest for a certain distance down the side, 
the amount of which is determined by the height of the inter- 
vening hill. Hence 

2. The crest of ridges form one of the lines of division 
between visible areas and dead ground. Note in Fig. 38 that 
the ridge line of the first hill, L, which can be easily drawn 
from the contours, forms the boundary of the dead ground, 
and that the upper boundaries of practically all the visible 
portions north of this hill are ridge lines. 

3. The lower boundary of the visible area will run along 
the sloping hillside facing the observer. Its shape will depend 



AREA PROBLEM 69 

on the form of the obstructing ridge nearer the observer, 
which prevents him from seeing to the bottom of the valley. 
If this ridge is practically level and not far above or below 
the observer, the lower boundary of the visible area will fol- 
low approximately a contour line along the farther hillside. 




Fig. 40.— Picture Plane. 

If the intervening hill is irregular in crest outline the boundary 
line on the side of the hill in question will show similar irregu- 
larities that can be completely determined only by drawing 
many radiating lines from the observer's station. 

In choosing where to put the radiating lines remember — 



Fig. 41. — Control Points for Sketch. 



(a) That a hill hides the country behind it, while 
(6) A sag or a gap permits us to see farther down on the 
next slope behind it. Draw the radiating lines so that some 
of them pass over the tops of hills and some through gaps, or 
sags. 



70 



HOW TO GET CERTAIN INFORMATION 



(c) Draw these lines only at critical or guiding places. A 
great number is not necessary in most cases, as only the general 
outline of the dead ground is required and irregular outlines, 
such as those on the mountain ridges on the sides of Fig. 38, 
are unimportant and can be put in by eye. \ 

The principles used in this problem of visible area may 
be used to make a landscape sketch showing the view of the 
hills and ridges from the point of observation. Thus if we 
held a transparent vertical plane in front of our eye, as indi- 
cated in Fig. 40, the lines of sight to the hilltops 1 and 3 
would intersect this picture plane at 2 and 4. Now if we 
imagine a plane of this kind, the edge of which is shown as 




Fig. 42. — Landscape Sketch Made from Map. 



PQ in Fig. 39, the points where the lines of sight Al, A3, A5, 
etc., cut this may be marked. By doing this for each of the 
radiating lines we secure the points plotted on Fig. 41 and 
these can then be connected up by eye giving the view shown 
in Fig. 42. This view will not be a "natural picture/' as the 
vertical scale used for the profile was much exaggerated, but 
it does give a clear idea of the view the observer would have 
if he stood on the hill at A in Fig. 38 and looked north. This 
illustration serves to show what complete data a topographic 
map gives us in regard to the country represented — we can 
make an exact model of the country from it and even draw 
pictures of the views we would see from different points and 
without making the model. 






SKETCHES AND MAPS 71 



PROBLEM 



Assume the point of observation is on the hill, about 1| miles west 
of A in Fig. 38, having an elevation of 950 feet (estimated, highest 
contour is 940). Draw six or seven radiating lines, plot profiles and 
plot out area visible. (Map shown in Fig. 13 may be used for this 
problem.) 



CHAPTER III 
USE OF TOPOGRAPHIC MAPS IN THE FIELD 

Art. 17. Coordinate and Grid Systems 

It is especially necessary in military work to have some 
simple system of referring to any point on a map and identify- 
ing this point on the ground or the reverse. It is usually 
very easy to describe a point in a general way, particularly 
if it is near a town. For example, we may speak of the "orchard 
\ mile south of Table Rock" on the Hunterstown sheet. 
Furthermore, we have used the number and letter system 
which is used in atlases and is given on this sheet. We can 
thus add to the above description C-7 which assists us in 
locating Table Rock. A description of this kind is clumsy, 
however, and does not permit us to describe points in detail, 
except by long descriptions and reference to more prominent 
objects. Various other, more definite, systems of reference 
have been devised and two of these, used by the English and 
French, respectively, on their war maps of the Western Front, 
will be described. 

The English system was a combination of lettered squares 
with coordinates for the final designation. It is known as a 
"grid system." The larger maps published by the English 
Survey Division, Dept. of Militia and Defense, were drawn 
to a scale of 1 : 40,000 and were published in sheets with an 
index number and letter. Each of these large sheets, one of 
which might be described as sheet 57c, for example, was 
divided into large squares or rectangles, each of which was 
designated by a letter, A, B, C, etc., as indicated in Fig. 43a. 
All of these lettered squares were divided into 30 to 36 smaller 
squares, as shown for Square H in Fig. 43a, 1000 yards on a 
side, numbered in much the same way as the sections are 

72 



COORDINATES AND GRIDS 



73 



numbered in the scheme of division of the U. S. Public Lands, 
and shown for Square H in Fig. 4>Sb. 

With the "grid" printed over the map it was possible to 
describe a point as being on Sheet 57c, large square H, small 
square 20, for example. Furthermore, each of the small 
numbered squares was again divided into four quarters lettered 
a, 6, c, and d as shown in Fig. 43c, which is supposed to repre- 
sent a large scale drawing of Square H 20 of Fig. 43b. A 



1-.40 000 


















Sheet 57? 


/A 


B 


C 


D 


E 


F 


G 














1 


J 


K 


L 
















-J 


-1 


1 


























M 


N 





P 


Q 


R 


S 


T 


u 


V 


W 


X 



1 


2 


3 


4 


5 


6 


7 


8 


9 


10 


11 


12 


13 


14 


15 


16 


17 


18 


19 


20 


InJ 
21 22 


23 


24 


25 


26 


27 


28 


29 


30 


31 


32 


33 


34 


35 


36 



(b) Numbering of Sub-divisions 
of. large Lettered Squares. 



(a) Sheet-Di vision 



c 1 1 1 i u r | i u t 1 1 n t 

I 



a i b 

! Y 



-20- 



« * 



d -- 



■jhni 



■ f r i | ] j r I i 

(C) Final Sub-division of 
: N umbered Squares 



Fig. 43.— The English Grid System. 



point could now be described as H 20c?, giving its location 
within 250 yards. This, however, was not close enough and 
for a final description within the small lettered squares, a, 6, 
c, and d, the coordinate system was used. That is, the sides 
of the squares a, 6, c, and d were supposed to each be divided 
into ten equal parts and to be numbered from the lower left- 
hand corner. The point X in Fig. 43c would then be described 
by stating first the number of these divisions to the right of 



74 USE OP TOPOGRAPHIC MAPS IN THE FIELD 

the zero corner and then the number up or 3, 6. This system 
permits a description to be written within tV of 250 or 25 yards, 
and when still more accuracy was required the coordinates 
were based on the division of the sides of the small squares 
into 100 instead of ten parts. The complete description of the 
point X wouM read Sheet 57 c, H 20 d 36. This grid system 
was printed at the proper scale on all the maps issued so that 
a description given from one map would be the same for all. 
Thus on the 1 : 20,000 maps the size of the squares was doubled, 
so that the larger squares would still be 1000 yards on a side 
as before and similarly for the 1 : 10,000 scale. 

The French system was a coordinate scheme pure and 
simple and no lettered squares were used. It is a better 
reference for artillery work, as distances may be computed 
directly from the coordinates, whereas in the English system 
it is necessary to change the data, as can easily be done, into 
coordinates. The English lettered and numbered squares, 
on the other hand, have the advantage of being easily under- 
stood and hence preferable for infantry where the men are 
not familiar with coordinates and liable to make mistakes. 

Fig. 44 shows the French system. Lines were drawn on 
the maps 1000 meters, or a kilometer (f of a mile) apart from 
the zero point, or origin, at 0. These divided the area into 
squares the dividing lines of which are numbered to the right 
and upward from the origin, thus giving their distances in 
kilometers from the origin. The description of a point is 
given by two series of figures, for example, the point A is 
described as 85.33. This means that the A is 85 hectometers 
(8.5 kilometers) to the right of the origin and 33 hectometers 
above it as shown by the dimensioned lines on Fig. 44a. Note 
that the distance to the right (known as the abcissa) is always 
given first with the distance up (ordinate), following. 

If a single sheet showed a map of the shaded area of Fig. 
44a the kilometer lines would be shown as illustrated in Fig. 
446. Remembering that the numbers on the lines are their 
distances in kilometers from the origin and scaling the dis- 
tances 5 and 3 to the nearest 100 meters over and up from the 
corner 8.3, by using the reading scale given at the bottom of 
the map we obtain the hectometric coordinates of A 85.33 



COORDINATES AND GRIDS 



75 



as given above. This locates the point A within a hectometer 
or about 100 yards. If this is not sufficiently acccurate the 
dekametric coordinates can be given by scaling the distances 
from the corner 8.3 to the nearest 10 meters. These might be 



o irt Tji eo eq 

















X 
















<*J 

















QO 



•C m 
bo a 

£ B 

B * 
S o 



M 



co oa 




S o 



52 and 34 and the dekametric coordinates would then be 
852.324. 

It is clear from the above that points shown on maps may 
be accurately described by either of these map reference 



76 USE OF TOPOGRAPHIC MAPS IN THE FIELD 

systems. The next article deals with the use of a map in 
the field, the location of points on the ground from maps and 
the reverse operation of locating points on a map from the 
ground. 

QUESTIONS 

1. Describe the location of the fork in a road indicated by the letter Y in 

Fig. 43c. Assume that this figure represents a sub-division oi square 
20 of large square P of Fig. 43a. 

2. Mark on Fig. 43a the approximate position of the point mentioned in (1). 

3. Describe the location of the cross-roads indicated by the letter X in 

Fig. 446 and mark its location on Fig. 44a. 

Art. 18. Use of Maps in the Field 

The ability to use a map intelligently in the field and obtain 
from it the required information is the main aim and object 
of the study of map reading. Real ability in this direction 
can only come as the result of practice in actually using maps 
in the field, solving the problems of location and identification 
which are met, and comparing the actual objects with their 
conventional representations on the map. Some of the prob- 
lems which may arise in connection with using maps in this 
way are briefly outlined in the following paragraphs. 

The first step when using a map in the field is to orient it 
as has been described in Art. 9. The object is to so turn the 
map that the direction of north on the map coincides with 
the direction of north on the ground and object shown on the 
map will appear in the same direction as the actual objects 
on the ground. 

The second step is to find on the map the position you 
occupy. This is not always as easy as it would seem and to 
be able to pick out a certain point on the map and say "I am 
now at this point" often requires considerable careful study. 
It is generally possible to locate the point we have come from 
and trace out our route on the map and in this way find out 
our present location. Special attention should always be given 
to keeping in mind the various landmarks that are passed 
during a trip. Certain buildings such as churches or schools 
which are shown by special conventional signs should be 
remembered. When the question of which turn to take in 



FIELD USE OF MAPS 77 

a road comes up, for example, and the map is consulted we 
first must find out where we are on the map, and it helps a 
lot in answering this question to remember that we passed 
a church about a mile back, or crossed a stream, etc. Even 
with these observations to aid us mistakes are often made, 
and no final location should be selected until the view in all 
directions from the actual point and the point selected on 
the map have been compared. There is a hill to the north- 
west, for example, with a lower hill to the east, etc., and 
these observations check with the contour indications on the 
map. Constant watchfulness and attention to details is 
required in many cases to locate one's position on a map, and 
it is well to remember that it is ordinarily not very difficult 
to find two or more places on a map that will fit a general 
description with fair accuracy. 

Under abnormal conditions this problem of location 
becomes very difficult indeed. For example, it happened 
in a number of cases in the war zone in France that parties 
fully equipped with large scale maps walked right through 
towns several times without being able to find them. This 
was due to the fact that the map showed a landmark that 
had been absolutely wiped out. It was necessary to put up 
signs in the field to assist in identification and a town was 
identified by a sign or the map reference such as A 20 c 68, 
of a point in the field was given by a sign to assist in location. 

Having oriented the map and found our location on it 
the next step is to identify other points and objects. In fact 
this, as indicated above, is generally a necessary preliminary 
to discovering our own location. In this connection direction 
is important (see Art. 9) and it is also desirable to be able to 
judge distances with a fair degree of accuracy. Again actual 
practice in the field in estimating distances to various objects 
and comparing them with the true distances scaled from a map, 
is the best practice. Attention to the clearness and relative 
size of such objects as trees, houses, telegraph poles, etc., 
helps in judging distances. 

Being able to judge the distance and knowing the direc- 
tion of an object it can be quickly recognized on the map or 
in the field. In mountainous country the problem of visi- 



78 



USE OF TOPOGRAPHIC MAPS IN THE FIELD 



bility (see Art. 15) is often of value in proving a certain 
location by noting whether objects in the field should or should 
not be visible according to the map. This is particularly 
valuable in identifying distant mountain peaks. 

Where the exact location of the observer is important and 
no object shown on the map is near by, the following method 
can be used. Some object shown on the map and visible 




HuMr 



^JW^^ 



L 



]Tmm£ 




Fig. 45. — Resection Method. 



in the field is selected and the observer paces, or measures 
with a tape, the distance to it and notes the direction with 
a compass. He then starts at this object as shown on the 
map and "plots" back the distance with the reading scale in 
the proper direction, thus locating the point in question. 
Another method, known as "resection" is illustrated in Fig. 
45. The map is placed in a horizontal position, preferably 
on a drawing board, and is correctly oriented. Two objects 



FIELD USE 79 

A and B visible in the field and shown on the map as a and 
b are selected. A ruler is placed on the map so that its edge 
passes through one of the objects, say a, and the ruler is 
turned so that it also points in the direction of this object 
in the field, A. An indefinite line is drawn for this position, 
ac, and the same procedure is followed for b and B, giving the 
line bd. The intersection of these lines at e is the location 
of the observer. Similar methods can be used to plot on the 
map the location of objects in the field and thus recognize 
them or complete the map if they are not shown. Such work, 
however, is properly part of the work of mapping and is treated 
in Part II. 

QUESTIONS 

See Hunterstown Sheet. 

1. You have been marching southwest from Hunterstown (D-5) for about 

three-quarters of an hour and have halted just beyond a schoolhouse 
near a small orchard to the east of the road. Find location on map. 

2. Draw a sketch to show the plan or map of a room. Orient the sketch 

and find your position in the room by resection from two corners. 



PART II 
SKETCH MAPPING 



INTRODUCTION 

Army officers must not only understand topographic maps, 
but must also be able to make simple military maps, the 
latter work being particularly necessary when operations are 
being carried on in a country where no large scale maps are 
available. The army engineers of course do most of this work, 
and in the operations on the Western Front in the Great 
War the maps were not only made but were printed in colors, 
with special equipment, by the engineer force in the field. 
Numerous minor sketches showing details of various posi- 
tions, etc., were made, however, by infantry officers, and the 
methods used in simple sketch board work are therefore of 
importance to infantry officers. The principles involved are 
also fundamental in the preparation of the "directing plan" 
and other features of "orientation" in artillery work. 

In civil life the ability to make a sketch map with simple 
instruments is of great importance in all kinds of prospecting 
work, particularly in geological or mining examinations. 

The methods used in sketch mapping are various and differ 
for different purposes. The following discussion of the subject 
does not attempt to give all methods or instruments used. 
Indeed only the simple army sketch case, which can be easily 
and cheaply secured,* is described, and its use in sketching 
developed. Other instruments and the methods used in 
extensive topographic work, such as the maps published by 
the different governments, engineering surveys, etc., are dis- 

* See Appendix 2. 
81 



82 SKETCH MAPPING 

cussed in books on surveying,* and a much more complete 
course of study and field training is necessary. 

It has sometimes been said that topographers are born, 
not made. It is undoubtedly true that some men possess 
much greater ability than others in making maps and sketches 
that represent faithfully the country mapped. Sketch map- 
ping in particular has often to be done under adverse con- 
ditions and time is not always available to take many meas- 
urements, so that a skilful topographical surveyor can do 
better and speedier work than a man who has not had this 
training. Practice and experience are the important elements 
to success in sketch mapping and proficiency can only be 
obtained by actual field experince. 

Before discussing methods of mapping it is necessary for 
a student to have practice in topographic drawing, and this 
feature of the work is therefore discussed first. 

* See for example Wilson's " Topographic Surveying." 



CHAPTER I 
TOPOGRAPHIC DRAFTING 

Art. 19. Freehand Lettering 

A large number of books* have been published on this 
subject and it will only be possible here to give a few notes 
on the most important points. 

Lettering is used on maps and in engineering work because 
it gives the desired information more clearly and compactly 
than writing. Contrary to the ideas of most students the 
ability to do very respectable freehand lettering can be quite 



ms 



MD[F6HIMMN0PQI?5T(JMXYZ 
akdefghj/fknopptumxyz 1234567890 

Fig. 46. — Inclined Lettering. 

easily cultivated and requires simply practice and attention 
to a few simple rules. Once acquired, freehand lettering will 
be found to be extremely useful for many kinds of work. 

One form of letter should always be followed and the best 
is the simple style shown in Fig. 46. The letters may be 
made in two ways — either vertical or inclined. These are 
equally good, and it is probably easier to learn the type which 
conforms to the slope of one's handwriting. 

Parallel horizontal lines, known as guide lines, should 
always be drawn to keep the lettering on line and assist the 
eye in keeping a uniform height of letter. In starting it is 
desirable to make the letters large, say one-quarter of an inch 
high, and practice the capitals first because these are easier 

* See particularly Reinhardt's " Freehand Lettering." 
83 



84 TOPOGRAPHIC DRAFTING 

than the small letters, as they require fewer curved lines. Pay 
particular attention to the form of the letters, carefully fol- 
lowing the simple shapes, proportions, etc., of Fig. 46 and 
omitting all flourishes, tails and other additions that begin- 
ners frequently add. Remember that good lettering cannot 
be done by a quick jerky motion of the hand or like hand- 
writing. A slow uniform motion with even pressure on the 
pencil or pen must be used, and it is desirable, particularly 
to avoid blots in pen work, to follow the order and direction 
of the strokes shown by the numbered arrows in Fig. 47. 
Note also that wide letters are not desirable, as they take 
more room; rather make the letters high and narrow. 

II \ > f , I, .1 I 8\V .■■!!■-•'■ I\ 91 f. 1. * 






n — 

y \ Ou'ide 
3L - <C; Line5 



Fig. 47. — Sequence of Strokes, Vertical Lettering. 

Students are often inclined to make the small letters too 
small in proportion to the capitals. After practicing with 
the capitals additional guide lines for the small letters should 
be drawn three-fifths the distance apart of those used for 
capitals. Here again a number of practice sheets should be 
made and care given to obtain the simple form and propor- 
tions with a uniform pressure on the pencil. 

The next step should be the combination of letters into 
words. The size of the letters may now be reduced to that 
which will actually be used in notes and data on maps. This 
should seldom be less than one-tenth of an inch for the small 
letters. "Microscopic" work should be avoided. In bringing 
letters together to form words special attention must be 



LETTERING 85 

given to the spacing between the letters. This is one of the 
hardest features of lettering, as the spacing is not uniform for 
all letters but must be varied not only for each letter, but also 
depend iug on the form of the adjacent letters. Spacing can- 
not be done by rule, but must be left to the eye. In general, 
keep the letters as close together as possible, in particular those 
adjacent to the letters A, V and Y, the round letters C, G, 
O and Q; also the letter before a J or following a P or L. 
The object is to make each word look like a single unit without 
any breaks or unevenness in appearance. 

EXERCISES 

The following exercises should be repeated several times 
and lettering should be practiced on scraps of paper during 
odd moments : 

1. Draw guide lines and letter a few alphabets of capital letters one-half 

inch high. After each attempt compare it for form, etc., with Fig. 46 
and correct the errors in the next. 

2. Do the same for the small letters except that they should be three-tenths 

of an inch high. 

3. Do the same for numerals, making them the same height as the capitals. 

4. Draw a series of guide lines for capitals about two-tenths of an inch 

high with small letters a little over one-tenth high. Select a paragraph 
from the text and do it in freehand lettering. 

5. Using guide lines as in (4) and giving special attention to spacing do the 

following in freehand lettering: " The attacking aeroplanes were flying 
very quickly." Note especially that most of these letters must be kept 
close together and that the A can be drawn partly under the head of 
the T, etc. 

Art. 20. Topographic Drafting 

One of the first steps in topographic mapping is to select 
a series of conventional signs. For formal publications, such 
as governmental maps, quite an elaborate series of signs in 
colors is appropriate, while for rapid sketch mapping in 
the field the signs used must be simple, easily made and 
suitable for pencil work. The former type has been discussed 
in Art. 3, Part I. Fig. 48 shows a very simple set of signs, 
which are practically those used on the war game maps pre- 
pared by the army schools at Fort Leavenworth. They are 
well adapted for field sketching with the sketch case. 



86 



TOPOGRAPHIC DRAFTING 



The student should review Art. 3 on conventional signs, 
particularly as regards the number of signs and the cor- 
responding detail in its relation to the scale of the map. 
Additional signs to supplement Fig. 48 should be taken from 
those adopted by the U. S. Geographic Board, which are prac- 
tically those of the U. S. G. S. 

Note that the size of each conventional sign depends on 



Pdads 

Oracled and bur -faced... 
Oraded not " 

Country 

Private...-: 

Path or Trail. 

Pbilroads 

Single Track 

Double " 

Street or Suburban. 
Bridges 
Culvert. 

Beam or Oirder. 

Truss. . h/'Wood s -steel . . 

Pile 

Buildings 

House ,. 

Barns and Outbuildings.. 

Ruins '. 

Church Ch= church .... 

Schoolhouse. .5H 

Station Sta 

Post Office... PO ,, 




***** 



Streams 
Under 15 ft Hide 
Over 
Ford 
Pitch 

Miscellaneous 

Telegraph line t 

Transmission-" ♦ 

Embankment. 

Cutting 

Land Classification 



a a a 






Trees nithout underbrush Woods with underbrush 



(SI 



\SH 



4 <*. 4 •«* i 



Windmill 

fences 

Barbed Wire 

Smooth 

Stone 

Worm 

Hedge... 

Cemetary. 



qPO 

1 * 

•5 



Brush 






OO O 
O O O 

o o o 


o 
o 

o 


o 

o 
o 


o 
o 
o 



P/neTrees and Rocks 





Orchard 






i 

i 


\ f 

f '"' 


f 





Marsh 



Corn 



Cultivated land 



>[_ + j All blank spaces are grass land 

Fig. 48. — Conventional Signs for Sketch Mapping. 

the scale used and at the same time seldom represents to scale 
the object it symbolizes. Buildings are shown correct in size 
and shape. The two lines representing the sides of a road, 
however, are not shown their proper distance apart except 
on very large scale maps — it would be impossible to draw two 
distinct lines, say twenty feet apart, on a map having a scale 
of one inch equals one mile, for example, while for a scale 



TOPOGRAPHIC DRAFTING 87 

of one inch equalling one hundred feet this can be, and is, 
done. 

Trees are never shown to scale and when in clumps or 
groups only the group is indicated. The exact number, that 
is individual trees, are shown only for isolated trees. Note 
the distinction between woods with and without underbrush 
as indicated in Fig. 48. 

EXERCISES 

1. Make a copy of Fig. 48 in pencil with freehand lettering for titles, etc. 

2. Take a sheet of paper and indicate by conventional signs in suitable 

position the following conditions: A macadamized road runs diagonally 
from the upper left to the lower right-hand corners, with common dirt 
roads running from about the third points towards the upper right and 
lower left-hand corners. At the junction of the upper of these roads 
and the main road there is a small town consisting of four stores, church, 
school, etc. The surrounding country is given over to farms with 
houses, outbuildings, orchards, cultivated fields with various kinds of 
fences, etc. Draw five such farms dividing the land in a suitable man- 
ner and introducing all the signs of Fig. 48. Suppose a large stream to 
cross the map about the center with bridge at road and branches from 
north and south. As an example of a map drawn with these signs 
see the Hunterstown map in the back cover. Note that this map has 
been reduced from a larger drawing and the size of the individual 
signs in this problem should be taken from Fig. 48. 

Art. 21. Enlargement and Reduction 

It is sometimes desirable to change the scale of a map, 
either enlarge or reduce it. This can be done by means of 
a special drafting instrument, the pantograph, or by the 
method of squares. The latter method is quite rapid and 
easy and involves both drawing conventional signs, as well as 
a problem in scales. 

Suppose, for example, we desired to enlarge one square 
mile of Fig. 13, a U. S. G. S. map drawn with an R. F. of 
1 : 62,500, so as to represent the square mile in question 
to a scale of 1 : 10,000. This might be done in order that we 
could use the data shown on the U. S. G. S. map as a basis 
for a complete military sketch. That is, we could enlarge 
this section, then go out in the field and sketch in a large number 
of details not shown on the U. S. G. S. map. 



88 



TOPOGRAPHIC DRAFTING 



The procedure would be as follows: 

1. Compute the length in inches which represents one 
mile on a map drawn with an R. F. of 1 : 62,500. (See Art. 9.) 

2. Draw a square with the above dimensions representing 



Fig. 49. — Enlargement by the Method of Squares. 



I 




r~i 



one square mile and covering the required section of the U. S. 
G. S. map. 

3. Divide this square into say twenty -five smaller squares 
by dividing each side into five equal parts. This may be done 



ENLARGEMENT AND REDUCTION 89 

by trial, with a scale (see Fig. 24) or by the method used in 
constructing a graphical scale. (Fig. 23.) 

4. Compute the length in inches which represents one 
mile on a map drawn with an R. F. of 1 : 10,000. 

5. Draw a square of this size on a sheet of drawing paper 
and check the angles to be sure it is a perfect square. Fig. 
49. Note that the construction of such a square is quite easy 
if a drafting triangle is available. If no instruments are avail- 
able fold over a piece of paper for a straight edge and lay 
out two sides of the square making a right-angled corner by 
eye. Check this in the following manner: Along one side 
lay off four inches and along the other three inches by means 
of the engineer's scale, Fig. 24, obtaining two points A and B, 
Fig. 496. Scale the distance between A and B. If this dis- 
tance is five inches the angle has been properly drawn. If 
it is not the lines should be corrected and again tested. Any 
fraction or multiple of 3, 4 and 5 can be used. 

6. Divide the square so constructed into twenty -five 
smaller squares as was done in (3). 

7. Transfer the details from the small map to the enlarge- 
ment by eye, square by square. For example, we note in 
Fig. 49a that the 800 contour crosses the center of the cop 
of the second square at a. 'This point is therefore marked at 
the center of the top of the corresponding square of the enlarge- 
ment at a! . The next point noted on this contour is where it 
crosses the corner at b which corresponds to b' in the enlargement, 
etc. Between these guiding points the line is drawn by eye. 

It will be noted that the small map could be enlarged to 
the larger scale by drawing simply the outlines of one mile 
squares and sketching in the details from the map to the 
enlargement by eye.. This would give a rough enlargement, 
but by dividing both the map and the enlargement into 
smaller squares the errors due to enlargement by the eye 
alone are reduced and such errors as do occur are practically 
limited to minor discrepancies in the smaller squares. 

EXERCISE 

1. Select any square mile of Fig. 13 and enlarge this portion of the figure 
to a scale of 1: 10,000 as described above. Give all computations on 
the reverse side of the drawing. 



CHAPTER II 
FLAT MAPPING 

Art. 22. Surveying and Mapping 

Surveying, of which mapping is a part, consists in making 
such measurements between various points on the ground 
as are necessary to plot the relative position of these points 
in the form of a map. Thus in making a map we want to show 
the location of houses, roads, etc., and this is done by deter- 





(a) Measurements. (&) Plotting. 

Fig. 50. — Mapping by Distance. 

mining the relative positions of points which define these 
objects, such as the corners of a house, points at bends in the 
roads, etc. 

In order to determine the relative position of points on the 
earth's surface measurements of distances, or angles and 
distances, are necessary. Fig. 50a, for example, shows a 
piece of land bounded by four straight fences. In order to 
make a map of the boundaries of this property we must 

90 



SURVEYING METHODS 



91 



determine the relative position of four points — the corners. 
That is, we must make in the field a sufficient number of 
measurements to enable us to plot these four points in their 
proper location on a map. The boundaries are simply straight 
connecting lines. Now if we measure the distance between 
each of these points, 1 to 2, 2 to 3, 3 to 4, and 4 to 1 it will 
not be sufficient to locate them, as there are an infinite num- 
ber of four-sided figures which can be drawn with these four 
distances as sides. If, however, we measure either diagonal, 
say 1 to 3, the figure is fixed, as this "tie line" divides it into 
triangles and when the three sides of a triangle are known the 




Error of . 
Closure 1 




(a) Measurements. 

Fig. 51.- 



(&) Plotting. 
-Traversing Method. 



corners are fixed. The map is plotted by laying off the length 
1 to 3 on our drawing to any scale which we wish to use for 
our map. Then, with 1 as a center we can draw a portion of 
a circle having a radius equal to the distance 1 to 4 to scale 
and with 3 as a center an arc of radius 3 to 4 to scale. Where 
these arcs intersect, as shown in Fig. 50b, is the location of 
the point 4 on our map. The same scheme of division into 
triangles may be used for areas of a greater number of sides. 

Fig. 51 shows another method of making a map of the 
same area. In this case the four angles are measured as well 
as the four sides thus fixing the figure. Angle measurements 
can be plotted by means of a protractor or Fig. 22c may be 
used for this purpose. That is, the measured length of 1 to 2 



92 



FLAT MAPPING 



may be laid off to scale. Then at the point 2 we may lay off 
the angle 1-2-3 by marking it on a piece of tracing paper 
held over Fig. 22c, and transferring our lines to the map. 
We then lay off the distance 2 to 3 in the direction so deter- 
mined, etc. Note that in doing this, as shown in Fig. 51b, it 
frequently happens that when we plot the point 1 from the 
point 4 it will not come exactly at the point we originally 
selected for 1 in starting our map. This may be due to small 
errors made in plotting or in the measurements themselves. 
Indeed we made two more measurements than were necessary 
to fix the figure — we could also have plotted the four points 
if we had not known the last distance or angle or, in fact, 





(a) Measurements. 



(6) Plotting. 



Fig. 52. — Mapping by Triangulation. 



with any one distance or angle missing. On the other hand, 
if we measure all the distances and angles, and plot them in 
the manner above described, and find that the plotting of the 
point 1 from 4 agrees very closely with our starting point it 
shows that our measurements and plotting were both well 
done and free from large errors, that is, the "error of closure," 
or distance between these two plottings, is a reasonable amount. 
In practice it will never be zero unless the errors accidentally 
balance. 

The above method of mapping by measuring all distances 
and angles is known as traversing. Another method, which 
is more rapid and better for certain kinds of work, is tri- 



PACING 93 

angulation. In this method we measure all the angles but 
only one distance, which is known as the "base line." Thus in 
making a survey of the field already discussed we would meas- 
ure any one side, say 1 to 2, and the angles 3-1-2 and 1-2-3 ; 
also the angles 4-1-3 and 1-3-4, Fig. 5%a. The length 1 to 2 
can then be plotted to scale, then the angle 3-1-2 can be laid 
off at the point 1, giving the direction of the line 1-3, and the 
angle 1-2-3 at the point 2, also giving the direction of the 
point 3. The intersection of these two lines, as shown in 
Fig. 526, determines the location of the point 3. The point 
4 is determined in a similar manner by plotting directions 
from 1 and 3 with the line 1-3 as a base. 

EXERCISES 

1. Given the following distances in feet between six points plot their loca- 

tion to the scale 1 inch equals 100 feet. 1-2, 260; 2-3, 273; 3-4, 94; 
4-5, 277; 5-6, 171 6-1, 298; 1-5, 317; 2-5, 356, and 3-5, 281. 

2. Given the following interior angle and distance measurements plot the 

traverse to the same scale as in (1). Distances in feet 1-2, 169; 2-3, 
122; 3-4, 76; 4-5, 221; 5-Q, 174; and 6-1, 204. Angles 1-2-3, 41° 30'; 
2-3-4, 277° 0'; 3-4-5, 108° 10'; 4-5-6, 60° 50'; and 5-6-1, 126° 0'. 

3. In Fig. 52 the base line measures 500 yards. The measured angles are 

as follows: 3-1-2, 68° 15'; 1-2-3, 76° 30'; 4-1-3, 32° 40', and 1-3-4, 
59° 10'. Plot the points to a scale of 12 inches equals one mile. 

Art. 23. Pacing and the Scale of Paces 

It will be clear from the preceding article that one of the 
fundamental operations in mapping or surveying is the meas- 
urement of distance. It is also clear from our studies of 
maps that maps show horizontal distances; that is, if we have 
two points on a hillside, such as A and B, shown in profile in 
Fig. 53, the distance between these points as shown on a map 
would be the horizontal distance AC, In making our meas- 
urements in the field it is possible to measure the horizontal 
distance directly by holding a tape on the ground at B and 
lifting the lower end sufficiently high above A so that the tape 
will be horizontal. It is also possible to measure the inclined 
distance along the line connecting A and B, and then by 
measuring the vertical angle BAC to compute mathematically, 
or plot up the triangle BAC and by scaling, get both the 



94 



FLAT MAPPING 



horizontal distance AC as well as the distance CB, which is 
known as vertical distance or difference in elevation between 
A and B. In connection with distances it should be always 
borne in mind that when we speak of distance we mean 
horizontal distance. 

In sketch mapping the method used for measuring distance 
is pacing. In measuring distance in this way two different 
plans can be followed: 1, by careful pacing between points, 
which have been accurately laid out with a tape, the pacer 
may so adjust his pace that he will learn to pace one yard. 
This method is largely used by surveyors who make consider- 
able use of pacing in locating the smaller details in topographic 



Vertical Distance 
or Difference 
in Elevation 




Fig. 53. — Profile Showing Distance Measurements. 

mapping and other work; 2, the pacer can use his natural 
pace and find out how many inches this is. Any distance 
can then be measured in paces and the number of paces con- 
verted to inches, feet or yards. The latter is the procedure 
followed in military and sketch mapping, because the first 
method, while very convenient, as the change from paces 
to feet or yards is simple, is artificial, and when the pacer 
becomes tired, as is the case when many or long distances 
are measured, he drops back to his natural pace. The sur- 
veyor, who measures only short distances by pacing, therefore 
uses an artificial step or pace of one yard. The sketch mapper, 
who frequently measures long distances by pacing, finds it 
desirable to use his natural step. 

To determine the natural pace or step a distance should 



SCALE OF PACES 95 

be measured out with the tape over level ground for the first 
practice. Having paced this distance and determined the 
average number of inches per step, a second series of distances 
should be laid out with tape over sloping ground. The pacer 
must now practice on these sloping distances so as to learn to 
lengthen his step by the proper amount in order that he will 
take the same number of paces as he would have taken had 
the ground been level. In other words, he must learn to judge 
slopes and how to lengthen his step so that he will secure not 
the sloping distance, but the horizontal distance between 
points. Inasmuch as the accuracy that can be secured by 
pacing is about 1 in 80 to 100, that is, a distance of 80 or 100 
feet or yards can be measured by pacing with the probability 
of the error not being over one foot or yard in either direction, 
it is unnecessary to give much attention in lengthening the 

For Pace =32 inches Scale 6 inches =1 mile 
100 100 200 300 400 500 600 700 800 900 1000 Paces 



0.3 inch each 

Fig. 54. — Scale of Paces. 

step on slopes of less than about ten or fifteen per cent. This 
means that any pacing along roads, where such grades are 
practically never found, no attention need be paid to length- 
ening the step. Also remember that we naturally lengthen 
our step when going down a hill and it is only necessary to pay 
particular attention to lengthening it when going up a slope. 

Having determined the length of the step it will be found 
convenient to make a scale of paces in order to simplify 
the plotting on a map of distances which have been placed. 
A scale of paces is similar to the reading or graphical scale on 
a map except that it gives distances on the map in paces in- 
stead of in feet, yards or miles. Thus if the map is to be drawn 
on a scale of 6 inches equals 1 mile and the length of pace is 
found to be 32 inches, we can make a scale which will enable 
us to plot paces directly on the map and save ourselves the 
labor of first converting paces into inches and then into feet 
or yards. The procedure in making such a scale is as follows: 



96 , FLAT MAPPING 

Taking one hundred paces as the largest division on the scale, 
this would equal 3200 inches on the ground, Since the map is 
to be drawn at the scale of 6 inches equals one mile (R.F. is. 
1 : 10560), it is clear that one hundred paces, or 3200 inches, 
would be represented by 3200 : 10560 or 0.30 of an inch on the 
map. The scale is constructed by ruling off successive lengths 
of 0.30 of an inch on a strip of heavy paper, marking these 
100, 0, 100, 200, etc., as shown in Fig. 54. The first space 
from 100 to is divided into 100 parts by the same method 
used for the graphical scale as already described in Art. 11. 

EXERCISES 

1. Lay off a length of 300 to 1000 feet with a tape over level ground and 

determine your natural step in inches. 

2. Construct a scale of paces with main divisions of 100 paces and an end 

portion graduated to read to ten paces for use in plotting a map the 
scale of which is 12 inches equals one mile. 

3. Select four or five points in the field, the corners of buildings, walks or 

other objects, and doing the necessary pacing, map them by pacing 
alone using the scale constructed in (2) above. 

Art. 24. The Sketch Case and Traversing 

In sketch mapping the distances are actually measured 
by pacing as above described, but the horizontal angles are 
transferred directly to the map and not measured in the 
usual units. In other words the plotting is done and the map is 
made in the field where this procedure is possible and where 
the sketcher has the land in view as he does the work. 

The methods of flat mapping will first be described, followed 
by the methods of locating contours. For contours elevations 
are necessary and these are secured by actually measuring 
the vertical angle, or the angle of one point above or below 
another. For this purpose either a slope board or clinometer 
is used as will be described in Art. 28. 

The instruments used for military mapping are contained 
in a small carrying case or sketch case* and comprise: 1. 
a small drawing or sketch board, 2. a light tripod, 3. a sighting 
scale or "alidade," 4. a slope board, and 5. paper, thumb 

* See Appendix 2. 



THE SKETCH CASE 



97 



SightingSca/e or Alidade 



Sketch Board 



Pencil 



Slope Board 

Front - — *- 
sho wing scale 
for vertical angles 



Carrying case 




Slope Board 
■— - Rear 
showing Reduction 
Diagram 



FIG. 55. COMPLETE. SKETCH CASE OUTFIT 



98 FLAT MAPPING 

tacks, pencil, eraser and pins. A complete outfit is shown in 
Fig. 55. The tripod may be fastened to the sketch board by 
means of a small thumb screw like that on any camera tripod. 
The board can thus be set up at any point, by moving the 
legs it can be approximately leveled by eye; with the thumb 
screw loose it can be turned in any direction, and by tighten- 
ing this screw is held firmly in any position. The drawing 
paper is secured to the board by thumb tacks. The tri- 
angular sighting scale or alidade is made of wood weighted 
with lead so as to prevent its movement by wind, etc. Pasted 
on its edges should be a reading scale for the map that is to 
be made, and scales of paces also corresponding to the scale 
of the map and to the pace-scales of the members of the 
party. In fact it is desirable that each man have an alidade 
with his own pace scale on it. This alidade serves three pur- 
poses: 1, it is used in transferring to the map the direction 
of various points from the point where the board is set up. 
2, the scales of paces on its faces are used in plotting distances 
on the map, and 3, the reading scale is used in scaling distances 
from the map. 

The two principal types of topographic surveys are road 
surveys and area surveys. The former, known as road map- 
ping in military work, has as its object the mapping of a nar- 
row strip of country on either side of a road or other line, 
while in the latter, known as position sketching, a topo- 
graphic map covering a certain area is required. Engineers 
make surveys of a similar nature, using more accurate instru- 
ments — the first for use in locating roads, railroads, canals, 
etc., and the latter in connection with plans for reservoirs, 
etc., which cover an area rather than a narrow line. 

The best method in using the sketch case is to do road 
work by traversing, and area work mainly by triangulation. 

The use of the traversing method for mapping a road 
is illustrated by Fig. 56, which represents a portion of a road 
with principal bends at B, C and D. We would set up our 
sketch board at A, Fig. 56a and turn and clamp the board 
so that its edges were about north and south as shown in the 
figure and so that the length of the board is in the general 
direction of the road. We now select a point on the board, 



TRAVERSING 99 

a, to represent the point A on the ground. Place a pin at the 
point a on the board and putting the triangular weighted sight- 
ing scale or alidade next to the pin turn the alidade so that 
it points at the next point B. A pencil line may now be 
drawn along the edge of the alidade, giving the direction of 
B. The distance to B is then paced and the point b, repre- 
senting B on the map is found by plotting the paced distance 




^B 



Road 



(a) 




B'Un'der b 




Fig. 56. — Traversing with a Sketch Board. 

with a scale of paces along the line drawn on the map from 
a in the direction of B. 

The board is now moved and is set up over the point B, 
Fig. 56b. The first step is to "orient" the board, or so turn 
it that it will be in a parallel position to that occupied at A. 
This is done by placing the edge of the sighting scale on 
the line ab, loosening the screw which secures the board to the 
tripod and turning the board so that the alidade, and hence 
the line ab, point back at A. The board is then clamped, the 
pin moved to the point b on the board, the alidade pivoted 
about b until it points at C and the direction of C from B is 



100 



FLAT MAPPING 



drawn. In this way the angle ABC is transferred directly to 
the map. We now locate c by pacing and plotting the distance 
be, move the board to C and repeat the operation. 

Note that the mapper must select the set-up points A, B, 
etc. These points should generally be taken as far apart as 
possible and at the principal bends in the road which can be 
sketched in freehand between them. Short sights are to be 
avoided in traversing with the sketch board, as they introduce 
errors in sighting. Also remember that it is necessary from 
each set up to see the previous point as well as a suitable point 
in advance. 

It will be found desirable to have at least two short poles 



<*?; 




Fig. 57. — Method of Sighting for Points Much above or below Level of Board. 



which can be stuck in the ground at the last and next set up, 
to use in temporarily marking them as well as in sighting. 
Also in sighting do hot stand close up to the alidade, but a 
few feet in back of it, as a better sight can be made this way. 
On steep grades, where one point is much higher or lower than 
the other, the beginner may have difficulty in sighting along 
the alidade. A pin may be put in each end of the top edge 
to assist in doing this, or a piece of string with a stone on the 
end may be held in the hand and used as shown in Fig. 57. 
The hand is moved until the string is on line with the eye, 
the board and the next point so that a glance down the string, 
without moving arm or head, will show whether the alidade 
is also on this line. 

The traverse shown in Fig. 56 begins at one point, A, and 



ERROR OF CLOSURE 



101 



ends at another point, B. It is an open traverse, inasmuch as 
it does not continue around and return to the starting point, 
thus forming a completed polygon or closed traverse. There 
is no check on the accuracy of an open traverse, but in the 
case of a closed traverse the error of closure, mentioned in 
Art. 22, gives a clear indication of the total error of the work. 
Thus in running a closed traverse we finally sight, pace, and 
can plot the location of the first point from the last. This 



2.% yds. / 

Mi 




Error of 

Closures 7^"* coincides 
10 yds. 7 \ a - 

z 



5 yds. 



Fig. 58. — Distribution of Error of Closure. 



location will not agree by a number of yards, probably by 
about one yard for every 100 yards' length in the traverse. 
The student should understand that an error of closure is 
always to be expected and that while a small error of closure 
indicates careful and accurate mapping it may not indicate 
efficient work. This is true because careful and accurate work 
requires time, and time is either valuable or costly. Hence 
the man who does work of a higher degree of accuracy than 



102 FLAT MAPPING 

is required for the purposes for which his work is to be used, 
is not economical in his labor and is not an efficient mapper. 

Recognizing, therefore, that an error of closure will 
always be present the next step is to distribute this error 
in a reasonable manner so that the map will "close" and its 
probable accuracy be increased. This can be done by drawing 
lines through each set-up in the map of the traverse parallel 
to the error of closure as shown in Fig. 58. Each plotted 
set-up point is then moved along this line by an amount pro- 
portional to its distance along the traverse from the starting 
point. In Fig. 58 the point a is left as it was; b is moved 
to &', as shown by the dotted line, by an amount bb\ 
which is one-quarter of error of closure a because the 
distance along the traverse from a to b is one-quarter 
of the total length of the traverse. Similarly, c is moved 
(500-M000) of 10 or 5 yards, etc. These adjustments can 
usually be made by eye. The final adjusted traverse is a, 
b f , c', d', a. 

In making a more complete map the details, such as 
houses, fences, etc., would be located from the various set- 
ups and drawn on the map. The various methods of doing 
this are described in the next article. 

EXERCISE 

1. Run a closed traverse with the sketch case as described above and adjust 
the same. Remember in selecting set-ups that it is necessary to see the 
last point as well as a suitable point in advance. Do not set up in the 
middle of a road or street as it will probably be necessary to move the 
board to allow traffic to pass and this means that the board will have 
to be oriented again. Not over three men should work together and 
the positions of plotter, pacer and rod man should be changed at 
frequent intervals. Accuracy and rapidity require an orderly and 
systematic scheme of work with each man thoroughly familiar with 
the procedure and trained to his part. Use a scale of 12 inches equals 
one mile. Show a pointer on the map drawn by compass or watch as 
described in Art. 9. Also letter a title, names of party and other suit- 
able marginal information. Set-up points should be marked by small 
circles. 



LOCATION OF DETAILS 103 

Art. 25. Location of Details 

The road map produced by traversing, as described in 
the last article, is of course devoid of all details and shows 
only the line of the road. This would also be true of a map 
produced by triangulation alone, which would show only the 
location of the set-up points in the area. Indeed the scheme 
of sketch mapping consists in locating on the map, by either 
traversing or triangulation, the point of set-up of the sketch 
board and then drawing in the surrounding details which go 
to make up the completed map from these points. 

In mapping by the traversing method three schemes are 
used to locate the details, namely: radiation, intersection and 
offsetting. Any detail, reasonably near the point of set-up, 
the distance to which may be easily paced, that is, the ground 
is fairly level and obstructions absent, is best located by 
radiation. This method, Fig. 59a, consists simply in drawing 
a "ray" from the set-up point in the direction of the object, 
the distance to which is paced and plotted in the usual manner. 
This is the same procedure exactly as is used in locating the 
next point in advance in traversing. 

It frequently happens that we desire to show on our map 
objects some distance from the point of set-up, hence requir- 
ing considerable time for pacing, and which may not be 
easily accessible from the set-up point. Such objects are 
located by drawing two rays towards the object from two 
different set-ups. For example, the building in Fig. 596 could 
be located by radiation if we paced the distance from the 
set-up point A to the object, but it will probably save time 
to locate this building by intersections simply drawing a 
ray toward it from the point A and when we occupy the 
station B, draw another ray toward the object, the intersec- 
tion of these two rays giving its location on the map. 

It will be evident that objects near the traverse line, 
but not near points of set-up, cannot be accurately or quickly 
located by either of the above methods. Intersections would 
give a poor location, ast he two rays would intersect at a 
very flat angle. For such details the method of offsets is 
best applied. Thus, in Fig. 59c, the building shown is best 



104 



FLAT MAPPING 



located by measuring the number of paces from A along 
the traverse line AB to a point directly opposite the object 
c and then pacing the distance at right angles to the traverse 
line, CD (known as the offset), to the object itself. In many 




( a) Radiation 



/ Ray drawn wfien. 
' ___ _at_B 




( b) Intersection 




^ (c) Offset 



Pig. 59. — Methods of Locating Details. 



cases it is unnecessary to actually measure the offset, as an 
experienced mapper can estimate it with sufficient accuracy. 

Students should understand that in the process of road 
mapping both the traversing and the location of details are 



LOCATION OF DETAILS 105 

carried on simultaneously and the details are mapped in 
from each set-up as the traverse is run. In order that the 
mapping may proceed rapidly and in a systematic way which 
will eliminate blunders the following procedure should be 
followed : 

1. Set up the board at the initial point selected for the 
first set-up, turn the board so that its edges are north and 
south, and by means of a compass or watch draw a north 
pointer for the map. 

2. Select a point on the board to represent the initial or 
starting point which the board is set up over. In selecting 
this point estimate where it had best be placed so that the 
map will not run off the edges of the paper. 

3. While the mapper is doing this, one of his assistants 
should advance and select the next station, marking it with 
a pole. Remember the requirements in connection with 
this selection and, in addition to those already mentioned, 
bear in mind that it should be chosen with reference to a 
view of the surrounding details, so that proper sights can 
be obtained to them to locate their positions on the map. 

4. The instrument man may now draw a ray to this next 
station while his assistant paces the distance. 

5. The mapper should now look over the section of country 
between him and the next set-up and decide which one of the 
three methods he is going to use in locating on the map the 
various required details. 

6. All objects which are to be mapped by radiation should 
now be plotted. 

7. Rays are drawn towards objects which will be located 
by intersection and a note is made on each ray describing 
the object sighted. 

8. After this work has been done it is best to place the 
alidade along the ray to the advance station and note if the 
board has accidentally moved during the work. 

9. Remove the board from tripod and hold it on the left 
arm. Sketch in all objects located by offsets as you walk 
up to the next station. One of the other members of the 
party should do the pacing, thus allowing the instrument 
man to give his full attention to the sketching. 



106 FLAT MAPPING 

10. Set up at the second point. Orient back on a pole 
left at the previous set-up and proceed to select a point in 
advance, etc., in the same manner as described above. 

EXERCISE 

1. The traverse run as in the preceding exercise should now be run as a 

complete flat road map, locating all details from each set-up as above 

described. 

Remember that it will be impossible, even with a large scale such as 

twelve inches equals one mile, to show all details, and that many details 

are of little or no importance. Do not fail to follow a systematic scheme 

such as is outlined above and make frequent changes in the assignment of 

the different members of the party to the various parts of the work so that 

each man will have practice in mapping, pacing, etc. 

Art. 26. Position Sketching 

If a closed traverse is run along a road surrounding a 
certain area of land, it will seldom be possible to locate all 
of the interior details of the area from the traverse sides. If 
a map is desired covering the entire area enclosed by the 
traverse, these interior details may be secured by running 
either spur traverses from points on the exterior traverse line 
to interior points, from which the interior details may be 
seen and located, or preferably by running several traverses 
entirely across the area and tying these into points on the 
exterior traverse, thus checking the work. 

Besides these methods we may also employ a combina- 
tion of traversing and graphical triangulation. When the 
object of the survey is to secure a mapped area rather than 
a narrow strip of country along a road, the method usually 
followed is triangulation, and such work is known in military 
mapping as position sketching. Remembering that the 
general plan of procedure is to locate on the map the point 
where the board is set up and from this point draw in the 
surrounding details before leaving for another point where 
the same process is repeated, it will be clear that the main 
problem is to locate on the map the point of the set-up and 
properly orient the board so that these side shots, etc., to 
the details may be taken. 

The steps in developing and using a scheme of graphical 



TRIANGULATION 



107 



triangulation for position sketching are illustrated in Fig. 
60 and given as follows: 1, select at some point in the area, 
preferably near its center, where a long strip of fairly level 
ground is available, a position for the base line. This base 
line, AB, should be of good length compared with the area to 
be surveyed. At least three, and preferably more, prominent 
objects (C, D, E) in this area should be visible from both 
ends of the line, and these should be well located for triangula- 



~#- 




\ Ray drown -fhrougn, 
^a from C in field 



\ Set up J 

\ T 

■ _____ --i—~""~ J \*--Xocated oy> 

\.Ray drawn \ Resectioa- 

p from b 

Set up 



Fig. 60. — Development of Triangulation Method. 



tion, that is, they should form good angles for intersections 
from each end of the base; 2, the base line is next carefully 
paced and drawn on the sketch board to scale, ab, and in such 
a way that the area to be mapped will not run off the edges 
of the board; 3, the sketch board is set up at one end of the 
base, A, and is oriented by placing the alidade along the 
base line and sighting at B, the other end of the line. A 
pointer is drawn by means of a compass or watch giving the 
direction of north; 4, a pin is placed on the map on point 



108 FLAT MAPPING 

a and rays are drawn with the alidade to the prominent 
objects C, D, E, etc. The topographer now proceeds to 
locate such details near the point of set-up as are suitable 
for location by radiation, and also may draw other lines for 
intersections; 5, the sketch board is now moved to the other 
end of the base line at B and oriented by sighting back on 
A. Rays are carefully drawn through b to the objects, C, 
D, E, etc., which are hence located at c, d and e by inter- 
section. Fig. 60. The topography near B is secured by radi- 
ation, etc., in the same manner as that near A. 

Having completed the mapping near the two points A 
and B, the mapper will have to move on to other points in the 
area from each of which he will locate the surrounding"details 
and thus complete the mapping of the area. While it is of 
course possible to traverse from either end of the base line to 
a new point of set-up it will very often be found that the 
distance to a desirable point of set-up cannot be easily paced 
and hence the mapper resorts to either the resection or what 
is known as the three-point method, which require no pacing. 

In using the resection method the next point of set-up 
F is selected and a ray drawn to it before the sketch board 
is moved from B. The board is now taken to this new point 
E where it is set up and is oriented by placing the alidade 
along the ray f'b previously drawn, and sighting back to the 
point from which the instrument has just been moved. The 
board is now properly oriented, but we do not know the loca- 
tion of our point of set-up on the ray f b. This may be found 
by placing the pin on the plotted position of some previously 
located object such as C, D or E, visible from the point of set- 
up. The alidade is now pivoted about the point c for example, 
and sighted at the corresponding object, in the field, C, 
which c represents on the map. A ray drawn backward 
from this point intersecting the previous ray will locate the 
point of set-up / on the first ray, /' b. Fig. 60. The point 
of set-up is now known and the board oriented, and the 
mapper may proceed to locate details. 

The three-point method, mentioned above, gives even 
more freedom to the topographer than the resection method, 
as it is not necessary to select the next set-up before leaving 



THREE POINT METHOD 



109 



a station. The mapper can pick up his board and move over 
the area until he finds a desirable position for the instrument. 
The board can be set up in this new position, oriented and the 
point of set-up plotted provided at least three objects already 
plotted on the map are visible in the field. 

Several methods are used for solving the three-point 
problem. One of the simplest of these is known as the trac- 




Fig. 61.— The Three Point Method. 



ing paper method, Fig. 61. A piece of tracing paper is placed 
on the board and held down with tacks. A point G is selected 
in the center of the paper and rays are drawn from this point 
in the direction of the three above-mentioned objects in the 
field, C, D, and E. The paper is now untacked and is moved 
around over the map until these three rays pass through the 
three corresponding objects c, d, and e, as plotted on the 



110 FLAT MAPPING 

map. It will be found that only one position of the tracing 
paper will satisfy this condition and the center point of the 
rays for this position of the paper gives the location of the 
point of set-up on the map. In Fig. 61 the map of Fig. 60 
is shown faintly by dotted lines while the three rays drawn 
on the tracing paper from the point of g are shown by solid 
lines. The position of the tracing paper illustrated shows 
the three rays passing through the three points as required, 
thus locating the point g. Before proceeding to the loca- 
tion of details it is necessary, however, to orient the board. 
This can be done by placing the alidade on any one of the 
three rays such as gc, and turning the board so that the ali- 
dade sights on the corresponding object C in the field. 

It will be obvious from the above description that the 
first thing to do in mapping an area by triangulation is to 
plan out a general scheme of procedure which will effectively 
cover the area to be mapped. It is also desirable to use as 
many checks as possible, such as intersections and resec- 
tions, to make certain of the location as the work proceeds. 

EXERCISES 

1. Complete the mapping of the interior portion of the area used in the 

exercise of the previous article. Do this by running cross and spur 
traverses introducing, if possible, at least one set-up by the three-point 
method. 

2. Make a position sketch of an area by the triangulation method including 

selection and measurement of base line, intersection, resection and the 
three-point method as described above. 



CHAPTER III 
CONTOUR MAPPING 

Art. 27. Contour Interpolation 

The methods of mapping previously described result in 
a flat map, showing the main topographic features of the 
country but devoid of relief. The problem of locating and 
showing on the map, by means of contours, the various hill 
and valley forms is more difficult and requires more skill and 
ability on the part of the mapper than the production of a 
simple flat map. 

The first step in contouring is to obtain a sketch of the 
drainage or stream lines. This is simply part of the flat 
mapping work and requires the location on the map of points 
at the principal bends in the streams so that they may be 
properly sketched in between. The relation of drainage to 
relief has been pointed out in Art. 5 and the necessity of 
obtaining a careful sketch of the drainage before proceeding 
to the contouring is quite clear. 

Having obtained the drainage lines the next step is to 
secure the location and elevation of certain controlling points 
which will enable us to interpolate and sketch in the contours. 
The selection of these controlling points and the method 
of securing their elevation is discussed in Art. 28. Their 
location on the map is secured by the flat mapping methods 
already described. The result of this work is shown in Fig. 
62a, which illustrates the drainage lines of a certain area and 
shows also the location and elevation of a number of these 
controlling points. This is sufficient to permit us to draw on 
our map suitable contours to represent the relief. In actual 
practice this work is always done in the field when the ground 
is in front of the topographer and the small variations in the 
form of the surface features can be noted and properly rep- 

lii 



112 



CONTOUR MAPPING 





X751 






X728 


#7X7 


V720 


X735 / 


726 X 


XL740 ^ 








N(708 


*72lX; 


£714 






X703 


X681 


698.X 





X751 






X728 


^717 


V-720 
720T 


X735 / 


726 X 


X740 


7^. /™ 






710 V708 


. 721 X. 


714 % 


y— WOO 




X703 


1 \ 
CO 1 

J: _4-.fi; 681 


698 
X 



(a) Drainage and Controlling Points as 
Located in the Field. 



(6) Interpolation of Contours along 
Stream Lines. 




(c) Interpolation of Contours along 
Ridge and Slope Lines. 



(d) Final Contoured Maps. 
Fig. 62. — Steps in Contour Interpolation. 



CONTOUR INTERPOLATION 113 

resented in sketching in or interpolating the contours from 
the drainage lines and elevations. 

As a preliminary practice in the work of drawing contours 
Figs. 62a, 63, and 64, which show the results of field measure- 
ments, can be used. The process of interpolation is as follows : 

1. Study the map and obtain a general idea of the main 
ridge lines in their relation to the valleys and to the given 
elevations. This will give us a general idea of how the con- 
tours will run and their general form. In connection with this 
study review Art. 5 in which the relation of drainage and relief 
is discussed. Bear in mind that contours will bend up the 
streams and down the ridges and that ridge lines must separate 
all streams. 

2. Locate the points where the contours will cross the 
streams in the following manner: Select any two adjacent 
points on a stream and assume the stream to have a uniform 
slope between these points, for example, the points 681 and 
708 in Fig. 62a. If we are placing 10' contours on this map 
there will be a 690 and 700 contour crossing the stream between 
these points. If the slope is uniform the stream must rise at 
a uniform rate, a total rise of 708 minus 681, or 27 feet between 
these two points. It is therefore true that a point on the 
stream having an elevation of 690 feet or 9 feet above the 
lower point will be located -h or i of the distance from the 
681 point toward the 708. We may, therefore, estimate by 
eye in Fig. 626, \ of the distance from the lower towards 
the higher point and mark this for the 790 contour. The 
800 contour being \\ of the distance or a little over f 
from the lower point toward the upper can be estimated in 
the same way, and may be drawn with sufficient accuracy 
at the f point or slightly above it. In connection with contours 
remember that the elevation of a contour must always be 
divisible by the contour interval. This method of interpola- 
tion should be followed out for all the streams and will result 
in locating the points where the contours cross the streams, 
as is illustrated in Fig. 626. 

3. No ridge lines are shown on this map, but by studying 
the drainage and noting the elevations we may draw such 
lines to be used only as construction lines in filling in the con- 



114 CONTOUR MAPPING 

tours. Thus, it is obvious that there must be a ridge dividing 
the two forks of the stream which branch out at the 708 point. 
This ridge will run as shown by the dotted line in Fig. 62c 
from the 708 point to the high point 735 and continue on 
through a saddle at 728 to the higher point 751 just beyond 
which it passes off the map. It is also clear that there must be 
higher ground on both sides of the stream and it will be 
assumed that the 726, 721 and 698 points on the right-hand 
side mark the crest of this ridge, while the same is true of the 
740 and 703 points on the left-hand side of the sheet. These 
points are therefore connected by dotted lines as indicated 
and contour points are interpolated along these lines in 
exactly the same manner as along the stream lines, Fig. 62c. 

4. Additional construction lines, running directly down 
the slopes, that is, approximately at right angles to the con- 
tour and drainage lines, are also drawn and contour points 
are located as before. The result of this work is shown in 
Fig. 62c. Note in connection with these latter lines, such as 
that joining the 721 point with the 708 point that they must 
be drawn directly down the slope, inasmuch as we assume 
the ground to have a uniform slope between them. It is 
obviously not permissible to interpolate between points like 
the 721 and 735, as such a line would cross the drainage and 
we know that two slopes would be involved, first a downward 
slope from 721 to the stream and then an upward slope from 
the stream to 735. Furthermore we could not join the 708 
with the 703, as this line would not run directly down the 
slope and as the 714 point in between indicates that a spur 
of the ridge runs out at this point requiring a decided bend 
in the contours. It is permissible to interpolate between two 
points only when the slope of the ground between them is 
uniform, i.e., when the profile of a line joining them would 
be a straight line. It will be clear from this discussion that 
the topographer must use care in selecting these controlling 
or critical points in the field and must so choose them as to 
properly define the ridges and abrupt changes in slope. 

5. Contours may now be lightly sketched in by joining 
the interpolated points having the same elevation on the 
various stream, ridge and slope lines. The spacing should 



ELEVATIONS 115 

then be adjusted and the final contours drawn in and numbered 
as shown in Fig. 6%d. It is in connection with the sketching 
in of the contours between these interpolated points that con- 
siderable thought and care must be exercised. This should 
always be done in the field where the sketcher can see the 
form of the hill or valley which he is mapping. This makes 
it possible to draw in and allow for many irregularities or 
peculiarities of form which cannot be attempted at all in an 
office exercise such as that given. 

EXERCISE 

Following out the method above outlined, (1) place 10' contours on the 
field sketch shown in Fig. 63; (2) place 5' contours on the sketch shown 
in Fig. 64. Note in particular in connection with this figure the swamp 
area which indicates a flat level section and the saddle in the hill in 
the lower right-hand corner at the 821 point. It is also true that the 
data given on these sheets is, in some places, insufficient to enable 
accurate contours to be drawn near the edges of the sheet. The prob- 
able form should be shown in such cases. 

Art. 28. Determination of Elevation 

Two steps are evidently necessary in order to secure the 
data essential in interpolating contours as described in the 
preceding article. One of these is the selection and plotting 
of the controlling or critical points and the other is the 
determination of the elevation of these points. 

The general plan for determining elevations is always 
to start from a point of known or assumed elevation, that is, 
a point the height of which above some datum, either sea level 
or assumed, is known. The difference in elevation between 
this point A, and another point B, is measured. It may be 
determined in several ways. Knowing this difference in 
elevation it is either added to or subtracted from the eleva- 
tion of A, depending upon whether B is above or below A, 
thus determining the elevation of B. B is now used as a start- 
ing point and the elevation of another point, C, is determined 
from B in the same manner, thus obtaining the elevation of 
successive points one from another. Obviously this vertical 
traverse may be continued around and closed back on the 
starting point, A, thus allowing us to check the error in the 



116 



CONTOUR MAPPING 



work. On the other hand a vertical traverse may be run as 
an open traverse without any such check, although it is 
always desirable to use as many checks as possible, averaging 
up the results obtained for each point and distributing the 
error in proportion to the distance traversed. 




Fig. 63. — Contour Interpolations Exercise. 



The difference in elevation between two points can 
be determined most accurately by means of a level instrument. 
Such an instrument consists of a level bubble, by means of 
which we can obtain a horizontal line of sight. Thus, in Fig. 
65 the difference in elevation between A and B is obtained 
by setting the instrument at some point between A and B 



ELEVATIONS 



117 



and taking readings on rods held at these two points. The 
difference in elevation is equal to the difference between these 
two rod readings, AC and DB. It frequently happens that 
more than one set-up of the instrument is necessary and an 
intermediate point has to be used in order to reach B. Work 




Fig. 64. — Contour Interpolations Exercise. 



of this kind is done with several types of instruments, the 
simplest of which is the hand level. Such work, however, 
while accurate, is not rapid and is therefore not suited to 
sketch mapping. 

In sketch mapping the method followed is to determine 



118 



CONTOUR MAPPING 



the vertical angle of one point above another, and, know- 
ing this angle and the horizontal distance, the difference in 
elevation can be computed or obtained graphically. To 
measure the vertical angle, either a clinometer or a slope board 




Fig. 65.— Spirit Leveling. 

is used. Several forms of clinometers have been devised by 
means of which the vertical angle can be quite accurately 
and rapidly measured, but the slope board is the simplest 
device available and though clumsy is quite as accurate as 
most clinometers. The slope board is shown as part of the 



toji 



0^i?S---^ 




Fig. 66.— Method of Using Slope Board. 

sketch case equipment in Fig. 55. It is also illustrated in 
Fig. 66, which shows the method of holding the board in the 
left hand while the plumb line is steadied by the right hand, 
the vertical angle being read on the scale at the lower edge 
of the board. 



MEASUREMENT OF ELEVATIONS 119 

When using the slope board it is held at the level of the 
eye, which is about five feet above the ground. In order to 
make the line of sight parallel to the inclined distance and 
obtain the true vertical angle it is necessary to sight an equal 
distance above the point B. In Fig. 67 the observer at A 
sights at his assistant at B and the line of sight FD is parallel 
to the inclined distance AB, hence the angle DFE equals 
the vertical angle BAC. The distance, DE, which is obtained 
by using the former angle and the horizontal distance AC, 
equals the true difference in elevation, BC. It is frequently 
inconvenient and it is unnecessary to send an assistant to 
stand at the point B which is sighted to. Instead of sighting 
at the correct distance above the ground level at B the observer 
can sight at the ground and correct the distance of elevation 



v**^~^' 



*' A 

Fig. 67. — Measurement of True Vertical Angle. 

so obtained by about five feet, thus allowing for the height 
of his eye above the ground. Note that this correction must 
be added to differences in elevation which are upward and 
subtracted from distances which are downward. In Fig. 
68 the vertical angle measured by the slope board is not the 
true angle and the difference in elevation obtained by 
using it is BD, while the true difference in elevation is BC or 
equals BD plus the height of the observer's eye above the 
ground DC. In Fig. 69 where the sight is downward, the 
difference in elevation obtained by using the angle measured 
with the slope board is DC which must be corrected by sub- 
tracting the height DA, as the true difference in elevation 
equals AC. 

In order to obtain the difference in elevation the hori- 
zontal distance is always necessary, as well as the vertical 
angle. This does not always require pacing the distance to 



120 



CONTOUR MAPPING 



the object sighted. A point may be located, for example, 
by intersections, in which case the horizontal distance can be 
scaled from the map by using the reading scale on the alidade. 
Indeed the diagram, Fig. 70, described below, requires that 




Fig. 68. — Correction of an Upward Sight. 

the horizontal distance shall be in yards, and it is therefore 
necessary to scale from the map the horizontal distances used 
in determining the difference in elevation. Knowing the 
vertical angle and the horizontal distance the difference in 




Fig. 69. — Correction of a Downward Sight. 

elevation is found by solving the right-angle triangle ABC 
of Fig. 53 for the side BC. That is, we may lay off the vertical 
angle BAC to scale and also the horizontal distance, and then 
scale off the height BC. Or we may solve this triangle by 
proper mathematical formula?. A large amount of time and 
labor can be saved by using a slope diagram such as that 



MEASUREMENT OF ELEVATIONS 



121 



133/ Nl 30NV1SI0 "IV0I1U3A 




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£ £ £ 

uj •* a. 

u. o 



122 CONTOUR MAPPING 

illustrated in Fig. 70, which consists simply of a drawing to 
scale showing a large number of vertical angles and horizontal 
distances which enable us to secure graphically the difference 
in elevation without making a separate drawing for each 
problem. If a horizontal distance, for example, is 500 yds., 
and the vertical angle is 3°, the difference in elevation may be 
read on the right-hand edge of the sheet as about 80 ft. If 
the distance had been 300 yds. the difference in elevation 
read in the same way would have been about 48 ft. Dis- 
tances greater than 500 yds. can be handled by the same 
diagram by dividing the distance in two or more parts and 
adding together the vertical distances obtained for each part. 

EXERCISE 

Determine the elevation of the different set-up points in the closed traverse 
used as the exercise in connection with Art. 24. Assume the elevation 
of the starting point as 100 or any other figure necessary to make all 
the elevations plus, that is, above datum. Determine the elevation of 
the points by using the slope board and the distance scaled from the 
map. Continue this process completely around the traverse and 
distribute the final error in elevation in proportion to the length of the 
sides. 

Art. 29. Contour Mapping 

The successive steps followed in securing contours have 
been dealt with in the last two articles. The student, how- 
ever, will find considerable difficulty in putting the process 
into practice in the field. He must first of all learn to do the 
reverse of visualizing relief from the contours. In other 
words he must learn to picture in his mind the proper contour 
forms for the different hills and valleys which he actually 
sees in the field and to sketch in these contours on his map. 
This will require considerable practice, and some men will 
be far more proficient in doing this than others. One of the 
most important points in contouring work is to analyze the 
relief visible from any set-up and to decide upon a suitable 
scheme of controlling or critical points which will give ade- 
quate data for the actual work of interpolating and sketch- 
ing in the contours themselves. 

The contouring, of course, proceeds continuously with each 



CONTOUR MAPPING 123 

set-up of the instrument in just the same manner as the 
location of details. It is probably best to locate the details 
first and then obtain the location and the elevation of the 
controlling points on the map, finally sketching in the con- 
tours just before leaving the set-up. It is seldom indeed 
that anything but the roughest kind of contours can be drawn 
from any one set-up without actually moving over the ground 
and noting its conformation.. For this reason the instru- 
ment man should call to the table his assistants who have 
been over the area and who can help him in the work of 
properly interpreting the relief by contours. It is desirable 
to use a colored pencil for the contours, as they otherwise may 
not show up properly or may be confused with other lines on 
the map. Where compactness and lightness of equipment 
is essential the additional slope board may be done away 
with and the sketch board itself used also as a slope board. 
The alidade may be used instead of a plumb bob and the 
slope scale and reduction diagram may be placed on opposite 
sides of the board. 

In locating the contours from any one set-up it is always 
desirable, as noted above, to have in mind a certain definite 
scheme or method of attack. For this reason it is well to 
proceed as follows: 

1. Having located the point of set-up and while securing 
the topographical details near this point by radiation or other 
methods, the instrument man should study the relief, noting 
the drainage and hill forms in order that he may have clearly 
in mind the points which he will adopt as controlling points 
for the contouring. Note in this connection that it will fre- 
quently happen that points located on the map to show topo- 
graphical details may also be suitably located for contour 
points. 

2. An assistant should use the slope board and by its 
means determine the elevation of the point of set-up, secure 
the vertical angles to various points already on the map 
which are to be used for contouring points, and compute their 
elevations. These elevations should be noted on the map 
by the mapper. 

3. The mapper should then proceed to locate additional 



124 CONTOUR MAPPING 

contour points while his assistant at the same time determines 
their elevations by means of the slope board. 

4. The contours are now interpolated exactly as described 
in Art. 27 and are drawn-in in the field, where the ground is 
in front of the mapper. Note particularly that contours which 
pass out of view or are in back of hills cannot be drawn with- 
out proper observations, and no contours should be guessed 
at which are out of sight unless special note is made of the 
fact that such portions are simply probable contours and not 
accurately determined. This may be done by showing such 
contours with a dotted instead of a full line. 

EXERCISES 

1. (a) Place a piece of tracing paper over the upper right-hand corner (say 

six inch square) of the Hunterstown sheet, which will be found in 
the back cover, and mark on this paper the drainage lines and what 
you believe to be the necessary controlling points to make a contour 
map of this area; (6) estimate the elevations of these points from the 
contours; (c) remove the map and interpolate contours from these 
selected points as described in Art. 27; (d) compare the contours so 
drawn with the original map. In this way obtain some practice in the 
selection of controlling points for different forms of relief. 

2. Contour carefully a small area, using the sketch and slope boards and 

showing contours alone. 

3. Complete the map used as an exercise in previous articles by filling in 

the contours of the entire area. 



PART III 
LANDSCAPE SKETCHING 



INTRODUCTION 

Landscape, or Panoramic Sketching, is used to a large 
extent in military work in making conventionalized pictures, 
particularly from artillery positions. These sketches show 
the enemy positions with approximate ranges and with de- 
scriptions of important targets. They are sometimes made 
by reconnaissance parties or again are made as a record of an 
enemy position for the information of the next detachment, 
or relief, occupying the position from which the sketch was 
made. 

A sketch of this kind is simply a conventionalized, outline, 
perspective drawing showing the view from any position, 
and with additional data in reference to the direction and 
range of important targets, such as points of special enemy 
activity, etc. The student should understand that a land- 
scape sketch is not an artistic effort. The work must often 
be done very rapidly and many sketches show only rough 
crest lines with indications of intervening ridges and hills. 
Only outlines are shown — the minute and smaller details 
being left out — and it is preferable to think of a landscape 
sketch simply as a map in a vertical, instead of a horizontal 
plane. It is drawn to scale just like other maps. 

In order to make a sketch four steps are necessary. 1, 
A system of delineations, or special conventional signs suit- 
able for this work, must be agreed upon; 2, the student 
must have some knowledge of perspective, as this is essential 
in putting these signs together so as to form even a rough 
landscape sketch; 3, inasmuch as the sketch is to be drawn 

125 



126 



LANDSCAPE SKETCHING 



RELIEF 




Mountain Skyline - Sharp , angular Hill Outlines - Smooth , rounding 
rounding downward. upward. 




Cliffs 



from beloH 




From aboye 



WOODS 





Elm Pine 




Cedor Maple Poplar 




Woods - Pack of crest -Jn foreground 
BUflPiN65* . 



Orchard 





house 



-Darn 



Church 



Factory Hindmill 



: " iL A, .wl 




**>* 



Farm 6 roup Tdnk Haystack 
'FEMES' ' 



Doard Fence 




darbed Wire 



Norm 



Stone 



Fig. 71. — Delineations. 



DELINEATIONS 127 

to scale and points must be shown in their proper relative 
position, particularly as regards direction, the sketcher must 
be familiar with the scale used; and 4, he must know how to 
locate on his sketch the main features of the landscape so 
as to secure guide points which will control the freehand 
work of sketching in the other features and give accuracy to 
the sketch. These various steps will be discussed in order. 

Art. '30. Delineations and Perspective 

As stated above delineations are simply the conventional 
signs of landscape sketching. They are not nearly as mechan- 
ical, neither have they been as thoroughly standardized or 
conventionalized as those used for "horizontal" maps, hence 
there is considerable opportunity for the sketcher to add to 
the neatness and appearance of his sketch if he possesses spe- 
cial ability in freehand work. On the other hand men with 
this ability frequently go to the extreme and try to show too 
much, while the novice goes ahead in a much cruder way and 
finally produces, not a "beautiful" sketch, but a simple outline 
drawing which is just as, if not more, useful. 

The main thing to work for in practicing delineations is 
a simple outline which will be suggestive of the object repre- 
sented. Figs. 71 and 72 show some simple forms which should 
be copied, not with the idea that they will cover all possible 
objects, but that they will suggest similar simple outline 
treatment for other objects. 

In order that the sketch may give a correct impression 
of the landscape represented it is necessary for the sketcher 
to give such effect of distance and perspective as his skill 
permits. The former effect is secured by drawing the delin- 
ations of the more distant objects smaller in size, just as these 
objects actually appear, with a fine light line and increasing 
the weight of the line used for objects nearer the observer. 
The rough outlines of one or two objects in the foreground 
frequently assists in securing the effect, but such objects should 
be sparingly shown, as they are of no importance except in 
this connection and in assisting to identify the point from 
which the sketch was made. 



128 



LANDSCAPE SKETCHING 



CULTIVATION • 




Plowed Land 



6m5sland 



S ^'^ "HBO. 

Oram 



■*#*? 



Corn 




Vineyard 




flrch 



foilroad ,efc. 



Stream and 
Swamp 



PERSPECTIVE 



Yam shiny fainf 




Fig. 72. — Delineations and Perspective. 



PERSPECTIVE 



129 



In connection with perspective it is particularly neces- 
sary that the student should understand the simple principles 
illustrated in Figs. 72 and 73. All parallel lines, such as the 
sides of roads, for example, or imaginary lines, such as those 
indicated in the sketch in the lower part of Fig. 72, appear 
to gradually converge as they become more distant from the 
observer and finally seem to meet at a point known as the 
vanishing point. Also note in this simple perspective how the 





PERSPECTIVE 



PLAN 




o d 



a b 
Fig. 73. — Perspective of a Circular Path. 



spacing of the poles of the telegraph line becomes smaller 
and smaller the further they are away. Now note the deline- 
ations shown above for fences, roads, etc., and how this same 
perspective effect is secured. 

Another feature in perspective is shown in Fig. 73. Imagine 
a circular driveway or track. The perspective appears wider 
in the foreground ah than at the back cd as shown in the 
sketch, due to the fact that the angle subtended at the eye 
by the two edges of the roadway is greater for the nearer 
portion. Also note that the sides at e and / appear their 



130 



LANDSCAPE SKETCHING 




J 



THE SKETCHING SCREEN 



131 



full width. Applying these same principles to the case of a 
winding stream we understand how the stream shown in Fig. 
72 is drawn. Fig. 74 shows a landscape sketch and illustrates 
how various delineations are combined to produce a clear 
drawing when due allowance is made for perspective effect. 
Note the varying size of the delineations and also the varia- 
tion in the thickness of the line used which, together with the 
rough indication of foreground objects, gives the effect of 
distance. 

EXERCISES 

1. Copy Fig. 71. 

2. Draw the required number of vertical lines one inch apart and horizontal 

lines at half this distance and enlarge Fig. 74 by the same process fol- 
lowed in the method of squares, Art. 21. 

Art. 31. The Sketching Screen 

The sketching screen is a device which is never used by 
the experienced sketcher but is of value in assisting the 




Fig. 75. — The Sketching Screen. 

beginner. It consists of a rectangular frame, as shown in 
Fig. 75, fastened to one end of a horizontal bar, the entire 
apparatus being mounted on a tripod. A series of vertical 
and horizontal cords divide the opening in the frame into 
rectangles. When this apparatus is set up, as illustrated in 
the figure, and the observer looks through the screen the 
vertical and horizontal cords will divide the portion of the 
landscape, viewed through the frame, into a series of rectangles. 
The extent of country covered by each rectangle will, of course, 



132 LANDSCAPE SKETCHING 

vary with the distance of the observer's eye from the screen. 
For this reason a peep sight is placed in a fixed position at 
the other end of the bar and opposite the center of the screen. 

In using the sketching screen a sheet of paper is ruled 
with vertical and horizontal lines just like the lines in the 
screen. The process of making a sketch from the landscape 
thus reduces practically to a problem of transferring the 
lines of the landscape to the paper, rectangle by rectangle, 
by a similar process to that used in the enlargement of maps 
by squares described in Art. 21. Thus seen through the 
screen a house is noted as being in the second rectangle from 
the left and third from the top and it is then drawn in its 
proper position in this rectangle on the ruled paper. It is 
of course unnecessary to transfer every detail from the land- 
scape to the pad in this way. The main points in the land- 
scape are located with the screen and the remaining details 
are drawn by eye, using these points as guides. 

The process of making a landscape sketch with the aid 
of the sketching screen is very simple and easily understood. 
The difficult part of the work is not in drawing delineations 
for simple isolated objects such as houses, trees, etc., in their 
proper position on the paper, but in "seeing" the lines of the 
landscape which are needed to represent the ground form 
properly in the drawing. It is best to start by locating say 
four or five of the most prominent objects as main guide 
points and then drawing the sky line and working forward, 
drawing only the ridge lines first and leaving out all trees and 
woods. The roads should next be drawn, then the fences, 
etc. Bear in mind that the effect of distance and form in 
the relief in the sketch is obtained almost entirely by draw- 
ing these objects curving over the hills and valleys as they 
appear in nature, with careful attention to their perspective. 
Be careful also to take full advantage of the weight of lines 
used to bring out the effect of distance. 

The next step in finishing the sketch should be the woods, 
which must be drawn with simple outline. Distant woods 
can be shown by a single line indicating roughly the out- 
line of the tree tops ; woods nearer the observer are indicated 
by rough outlines of the most prominent trees. Woods should 



THE SKETCH PAD 133 

never be drawn so as to cover up other details that can be 
clearly seen by the observer. 

In finishing a sketch of this kind remember that, while it 
is called a sketch, this does not mean that the lines of the 
drawing can be made carelessly or too freely. As already 
stated such a sketch is essentially a map drawn in a vertical 
plane, and the same care must be used in drawing the lines of 
this sketch as is exercised in drawing the usual conventional 
signs or in doing freehand lettering. Use a slow uniform mo- 
tion of the pencil which will give a sharp, definite line and 
omit all shading or other lines which have no definite purpose 
or indication in the sketch. 

EXERCISES 

1. As a practice in analyzing a landscape, and choosing simple outlines to 

represent its main features, select several photographs or magazine 
pictures of simple landscapes, place a piece of tracing paper over each 
of them in turn and trace the outlines necessary to show the main 
features. 

2. Construct a sketching screen as described in Appendix 2 and practice 

with this apparatus in the field, Select simple views from hill- tops or 
positions where quite an extensive outlook can be had. Detailed 
sketches of objects very close to the observer are not desirable. In 
artillery work the important part of a sketch is usually a target a mile 
or more distant from the observer. In machine-gun work the middle 
distance is important. The foreground is of value only in infantry 
work, where the ground to the objective must be traversed by the 
troops and the best route as regards going and cover is to be selected. 

Art. 32. The Sketch Pad 

The sketching screen, while accurate and very useful 
to the beginner, is clumsy and cannot be easily carried in the 
field. For this reason it is not used by the experienced sketcher. 
The horizontal and vertical lines on the sketch pad, with the 
aid of a piece of string, can be made to serve the same purpose. 

Fig. 76 shows a page of a sketch pad in reduced size. 
The actual pad consists of a stiff cardboard back, 6| by 9 
inches in size, to which a number of the printed forms shown 
in the figure are fastened. The vertical lines on these forms 
are one inch apart and the horizontal lines one-half inch. 
The lettering, etc., on the forms is described in Art. 33. 



134 



LANDSCAPE SKETCHING 



A piece of string is fastened to the bottom of the pad and 
a knot is put in the string at twenty inches from the pad. 
In using the pad the end of the string is held in the teeth and 





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Date: 

Name: 

Weather: 


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the pad in the left hand. Thus the string fixes the distance 
from the observer's eye to the pad, just as the peep sight does 
with the sketching screen, and the lines on the pad itself 



THE SKETCH PAD 135 

take the place of the frame and strings of the screen. The 
pad, not being transparent, has to be used in a slightly different 
manner than the screen. That is, we locate points of the land- 
scape in their proper position on the pad not by sighting through 
it but by noting their positions along the top and side edges 
of the pad. The procedure is as follows : 

1. The sketcher selects some prominent point on the land- 
scape as a "reference point" and locates this point at the inter- 
section of one of the vertical with one. of the horizontal lines 
of the pad. 

2. Other prominent, or guide points, for the sketch are 
first located on or between the proper vertical lines, to the 
right or left of the reference point, by using the top edge of 
the pad as a scale. Thus with the pad held vertically, twenty 
inches from the eye, and with the selected vertical line directly 
under the reference point on the landscape, we note, by 
sighting along the upper edge of the pad, that some promi- 
nent object is two and one-half vertical spaces to the right 
of the reference point. Now holding the proper horizontal 
line even with the reference point and sighting down the 
vertical edge of the pad we see that this same object is, say, 
one horizontal space below the level of the reference point. 
The intersection of two lines, the first a vertical line two and 
one-half spaces to the right of the reference vertical and the 
other the horizontal line below the reference point, deter- 
mines the location of the object on the pad. 

3. Having located in this manner on the pad a number 
of the main points of the landscape the observer proceeds 
to sketch in the landscape as previously described. 

In many cases it is desirable, in order to get more space 
and hence a clearer sketch, to exaggerate the vertical scale 
of the drawing. For example we may note the number of 
horizontal spaces an object is above or below the reference 
point and then double this value when plotting its location 
on the pad. This procedure is similar to that followed in mak- 
ing profiles. The effect on the sketch is to make it appear that 
the observer had made the sketch from a much higher eleva- 
tion than he actually occupied. 



136 LANDSCAPE SKETCHING 

EXERCISE 

Following the hints given in regard to the selection of landscapes in Art. 
31, a number of sketches should be made, using only the sketch pad. 

Art. 33. Descriptions and the Mil Scale 

Fig. 77 shows a landscape sketch with the complete data 
as regards location, etc., filled in. Thus the arrow, drawn 
from the cross mark at the center of the bottom of the pad 
shows the direction of north. The view illustrated in the 
figure therefore shows the country in a northwest direction. 
Place, date and name need no explanation. Weather and 
time are sometimes important on account of the clearness 
and extent of the view under different atmospheric condi- 
tions and lighting. 

The lettering at the upper left-hand edge of the pad is 
used in describing various important points of the sketch. 
T stands for target and in the horizontal space provided 
a brief description of an important target such as "red house," 
"machine gun emplacement," etc., can be given. RN stands 
for range or the distance in yards from the observer to the 
object. This may be scaled from a map, estimated, or deter- 
mined in some other manner. The abbreviation DF is for 
deflection, or the angle to the right or left of the reference 
point, which point is shown by an arrow and marked zero. 

In measuring deflections, or angles, in military work it is 
the practice both in the United States and in France to use 
a special unit instead of the usual degrees, minutes and sec- 
onds. The scheme used is known as the Mil System or 
Scale and all instruments used, such as angle measuring 
instruments, protractors, etc., are divided in this scale. A 
mil may be defined as the angle formed at a point by two 
lines, each one thousand units long, and one unit apart at 
their far ends. Thus the angle between objects one yard 
apart and distant one thousand yards from the observer is 
one mil. A mil represents an angle of about 3 J', but being a 
ratio (the ratio of the base of a triangle to its altitude) a 
number of calculations are simplified,* or can be solved approx- 

*See Danford and Moretti, "Notes on Training Field Artillery Details," Yale Press. 



DESCRIPTIONS 



137 



imately with great rapidity. The system is also used in 
directing rifle fire.* 

The angular distance in mils of two points at different 




distances can be easily found. For example the angle between 
two points ten feet apart and one thousand feet distant is 

* See Moss, " Manual of Military Training." 



138 LANDSCAPE SKETCHING 

ten mils. If these points had been only 500 feet distant 
the angle would have been twenty mils, because a ratio of 10 
in 500 corresponds to 20 in 1000. Thus the vertical lines of 
the sketching screen, being one inch apart and twenty inches 
from the eye, determine an angle of fifty mils (1 in 20 or 50 
in 1000). The same relation is true for the lines of the sketch 
pad, and the scale of our landscape sketches may therefore be 
said to be fifty mils to an inch. 

EXERCISES 

1. Make a landscape sketch of a section of country of which a map is avail- 

able. Give complete data on sketch including description of important 
points and ranges scaled from the map. 

2. A train is ten cars long and the average length of a freight car is forty 

feet. The angle at the observer is measured and found to be eighty mils. 
What is the range? 



APPENDIX 



1. A DESCRIPTIVE LIST OF THE PRINCIPAL TOPOGRAPHIC 
MAPS OF THE WORLD 

By F. K. Morris 

Instructor in Geology, Columbia University 

Modern survey maps have been a gradual development. Anything 
less than a complete history is necessarily unjust to some of the earlier 
cartographers, upon whose labors and errors the later and better methods 
are in some degree founded. Perhaps the past suffers the least wrong if 
we date modern national survey maps from the labors of the Cassinis in 
France in the eighteenth century. Before that century opened, Picard, 
Lahire and the elder Giovanni Dominico Cassini had made careful measure- 
ments of the length of a degree in France and had commenced the work of 
accurately determining the position of many points by astronomical methods. 

In 1739 Cesar Francois Cassini, grandson of G. D. Cassini, began what 
is essentially the first national survey of a large country, basing his "Carte 
geometrique de la France" upon careful triangulation. His son, Jean 
Dominique, carried on and completed the work in 1789. The scale was 
1 : 86 400. The topography was shown by means of shading and rather 
imperfect hachure lines, in which we trace the influence of the old "picture 
maps" whose mountains were mere perspective drawings of mountains. 
It was a mighty achievement; the record of a great area on maps of uniform 
scale, a definite system of topographic symbols — but it was not yet strictly 
a national survey, for the government had no part in the work. Several 
other European states commenced primary surveys during this century; 
and according to Dr. M. Groll, several of the small German states had 
officially prepared maps even before those of Cassini were issued. None of 
these were published, but were held as military secrets. 

National surveys became a necessity of the first order during the wars 
of Napoleon. Napoleon's engineers mapped Savoy and northern Italy, 
and parts of Germany and Austria. During his brief stay in Egypt, a sur- 
vey in fifty sheets was undertaken. A new national map of France was 
planned to replace the older map of the Cassinis. It was to be called the Carte 
de France de £'ltat-Major, to be mapped on the scale 1 : 20 000 and issued 

139 



140 APPENDIX 

on the scale of 1 : 80 000. The actual work was commenced in 1818 after 
the fall of the Empire. The British Ordnance survey, which had been 
planned as far back as 1745, quickened into life under the impetus of the 
Napoleonic struggle, and the work of surveying England was carried on at 
the same time that France was making the Carte de l'Etat-Major. From 
that time to the present, national surveys have developed in all countries. 

EUROPE 

FRANCE 

Carte de France de l'Etat-Major. 1:80 000. See "Guide Pratique 
pour la lecture et l'emploi de la Carte de L'Etat-Major." By Major fimile 
Esperandien. 1915. 

This is the map planned by the great Napoleon as the successor to the 
Cassini map. The work was begun in 1818, finished in 1856, and revised 
and reissued since. Se3 Fig. 7. 

The maps are rectangular and so are not oriented exactly north and 
south. Parallels and meridians are printed upon the face of the map at 
intervals of ten decigrads. A scale of latitude and longitude runs around 
the margin of the map and is subdivided in degrees and minutes and also 
in grads and centigrads. The sheets are numbered continuously from 
west to east, beginning with No. 1 at the western end of the northernmost 
row of adjacent sheets, and ending with No. 258 at the eastern end of the 
southernmost row. There are 258 sheets for continental France — 267 
including Corsica. Each sheet covers about 64 km. E. and W. by 40 km. 
N. and S. 

Relief is shown by means of black hachures, with great numbers of spot 
heights in meters above sea level. The conventional signs used are shown 
in Fig. 6. 

In its day this was undoubtedly the best national map in the world. But 
it was speedily improved upon by later surveys in other countries. 

Carte de France de l'Etat-Major. 1 : 200 000. 

Sheets are bounded by rectangular lines and numbered as in the older 
edition. A scale of latitude and longitude is plotted along the margin of 
the map, and subdivided to centigrads. There are seventy-eight sheets 
for continental France, eighty-one including Corsica. Each sheet is about 
128 km. in width from E. to W., and 80 km. in length from N. to S. 

Relief is shown by contour lines of 20 m. interval. Every fifth contour 
is emphasized by being printed more heavily than the others, but the con- 
tours are not numbered as on the American maps. Spot heights are printed 
in black with sufficient frequency to enable one to read the contours without 
much difficulty. Hillsides are shaded, the shading being strongest on the 
southeastern side as though hills were lighted from the northwest, 



APPENDIX 141 

First-class roads are shown in red lines of two widths. Second-class roads 
kept in less regular repair are red dotted lines. Dirt roads are a single 
black line, and dotted lines indicate footpaths. Buildings are black blocks, 
but not all buildings can be shown separately upon a map of this scale. 
Separate symbols are printed for church, shrine, chateau, tower, ruin, for- 
ester's lodge, windmill, watermill, factory, fort. 

All waterbodies are blue, and the largest ones are water-shaded. Canals 
appear as double lines of blue. The only vegetation-symbol is the green 
area that represents forest. 

This map served as the base map for both the airplane map prepared 
by the Aero Club of France, and for the better airplane map issued by the 
Service Geographique de l'Armee. It is a work of the highest value, showing 
large areas and bringing out clearly and graphically the important features 
both of relief, culture, and forest cover. 



New Carte de France de l'Etat-Major. 1 : 50 000. See Frontispiece. 

Sheets are bounded by meridians and parallels and so are not quite 
rectangular. These are printed on the map one decigrad apart; and along 
the margin of the map there is a scale of grads subdivided to centigrads, 
and a scale of degrees subdivided to minutes. Both scales take their origin 
at the Pantheon in Paris. Each sheet covers about 30 km. E. and W. by 
20 N. and S. 

The rows of adjacent sheets from E. toW . are called Zones, and each 
zone bears an Arabic number beginning with zone 1 at the northernmost 
coast of France and ending with zone 50 at the southernmost Pyrennees. 
Vertical rows of sheets from north to south are called columns, and each 
vertical column is numbered in Roman numerals beginning with column I 
beyond Cape Finisterre at the westernmost limit of France, and continu- 
ing through column XLII.I, which lies far enough east to include the part 
of Alsace taken by Germany in 1871, and now restored. Each sheet thus 
bears two numbers — its zone number and its column number. For example, 
the Paris sheet is Feuille XXIII-14. 

At present writing only forty-two sheets have been issued, and eleven 
more are in preparation. The published maps include nine about Paris, 
two at Soissons and La Fere, nineteen near the former frontier from Nancy 
southward past Belfort, two at Lyons, and nine scattered along the south- 
ern coast. 

Relief is shown in brown contours, vertical interval 10 m. Hillsides 
are shaded so that the topography is very easy to read. Spot heights are 
printed in black with an appropriate symbol to show how the elevation was 
determined. Water-bodies are colored blue and the larger ones are water- 
shaded. Canals are double lines of blue. Buildings and fortifications appear 
in red. The population of each town is printed in red near its name. There, 
are separate symbols for church, chapel, cross, mayor's office, police station, 
hospital, and for industrial plants driven by steam or by water power. 



142 APPENDIX 

In black, there are symbols for post, telegraph, and telephone offices; and 
for kilns, plaster burners, quarries and mines. 

Forests are light green, vineyards are purple, meadows light blue and 
gardens are shown in turquoise blue lines. Black dotted areas are orchards. 

This map is unique among all national maps in the use of color and for 
the skill with which minute detail is shown without in the least crowding 
the map or interfering with its simplicity and legibility. 



GERMANY 

Karte des Deutschen Reiches. 1 : 100 000. See " Kartenkunde " by 
Dr. Groll. 

Sheets are bounded by parallels and meridians. The longitude is cal- 
culated eastward from Ferro, an island in the Atlantic Ocean off the west 
coast of Europe. Each map covers an area about 33 km. E. and W. by 28 
km. N. and S. Six hundred and seventy-four sheets complete the German 
Empire as it was before the Great War. The sheets are numbered con- 
secutively from west toward east beginning with the northernmost row 
of maps along the Baltic shore of East Prussia, and continuing, as on the 
French map, to the eastern end of the southernmost row. A scale of lati- 
tude and longitude in degrees, subdivided to minutes, runs around the 
margin of each sheet, but no parallels or meridians are printed upon the 
surface of the map. 

Relief is shown by hachures printed in black with a great number of 
spot heights in meters above sea level. 

Rivers appear as either single lines or double lines, the width of the 
symbol proportionate to the width of the stream. Lakes are blank spaces 
on some of the sheets and on other sheets have horizontal shore shading. 
Dotted contours indicate the depth of water. Canals have double lines 
on each bank. 

Houses appear as small black blocks, either rectangular or shaped like 
the ground plan of the building. In addition at least ten separate symbols 
for special buildings have been devised, and the significance of these is 
increased by means of abbreviations printed besides the symbol. The 
church, chapel, windmill, watermill, stampmill, forester's lodge, watchtower, 
ruin, fort, monument, quarry, claypit, limekiln, coke-oven — all have sep- 
arate symbols. Factories, brickworks, powder magazines, electric power 
plants, and many other important buildings are indicated by means of 
abbreviation. Symbols for walls and hedges, and even separate symbols 
for Christian and Jewish Cemeteries have been devised. Four different 
qualities of traffic road are indicated, as well as bridle paths and footpaths, 
but there are only two symbols for railroads, — one for tramways and the 
other for all other railroads. Separate symbols for bridges with wooden 
supports, with iron supports, and with boat supports are used, and there 
are three separate symbols for ferries. 



APPENDIX 143 

The vegetation is minutely classified. There are separate symbols 
for trees with broad leaves, such as maples, oaks and beeches, and for the 
evergreens, for underbrush, for heather, for dry meadows and wet meadow, 
for swamps, for orchards, hop gardens, vineyards and parks. 

The map is engraved and printed with great care. Its small scale and 
black color are great disadvantages, but it gives an extraordinary amount 
of minute information about the country. Its entire plan is borrowed from 
that of France, and only the more minute subdivisions of symbols can be 
regarded as a contribution to Cartography. 

Karte des Deutchen Reiches. 1 : 100 000. Colored Edition. 

This map is exactly like the black map of the same scale with the fol- 
lowing exceptions: 

The hachures are brown and 100-m. contours, in brown, are printed upon 
them, immensely improving the quantitative value of the relief symbols. 
The hills are shaded on their southern faces, so that all three common 
methods of expressing topographic relief are combined upon this map, 
yet the designing and engraving is so accurate that the map does not appear 
overcrowded and the hills stand out very clearly. The symbols for water 
are blue, the lakes being covered with fine horizontal blue lines. In the 
deeper lakes contours are printed in black as well as a figure indicating 
maximum depth. Glacial ice has a blue symbol not unlike that of Swiss 
maps. 

Karte des Deutchen Reiches. 1 : 25 000. 

The sheets are bounded by parallels and meridians including 10' longi- 
tude and 6' latitude (11 by 11;H2 km.) Longitude is reckoned eastward 
from Ferro. The maps bear as title the name of the principal town, as 
they do in our U. S. G. S. maps. In the bottom margin of many of the 
sheets there appears a very small index map showing where this particular 
sheet would lie upon the numbered sheet of the map on the scale of 1 : 100- 
000. The complete map would contain about 5,055 sheets. 

Relief is shown by means of contours, with an interval of 5 m. Each 
fifth contour is emphasized by being printed a little more heavily. Where 
relief is slight, additional contours are introduced between the normal ones. 
These accessory contours or "Hiilfskurven" are dotted lines and have a 
vertical interval of 1.25 m., so that even the most inconspicuous rolls of 
ground-surface can be expressed. Spot heights are printed as close together 
as 1000 m. 

Lakes and large rivers appear as white spaces with black line margins. 
Small streams are single lines whose thickness is proportional to the width 
of the stream. The symbols for culture are essentially the same as those on 
the 1 : 100,000 map, except that lawns and grounds around buildings are 
covered with parallel ruled shading. A far greater variety of labels and 
abbreviations increases the expressiveness of this map as compared to that 



144 APPENDIX 

on 1 : 100 000. The symbol for fort is larger and more complex, suggesting 
that actual shape of the defensive work. The symbols for vegetation are 
the same as those of the 1 : 100 000. 

On some of the sheets, soundings and contours at 2, 4, 6, and 10 m. 
intervals are printed in the larger water bodies. 

AUSTRIA-HUNGARY 

Spezialkarte der Osterreichisch-Ungarischen Monarchic 1 : 15 000. See 
" Das Kartenlesen " von Gabriel Tambri. Innsbruck, Heimrich Schwick, 
1912. . 

The sheets are bounded by parallels and meridians, each covering 15' 
of latitude and 30' of longitude (28 by 38 km.). Longitude is reckoned 
eastward from Ferro. The entire map is in black. 

Rows of sheets from east to west are called zones, and the zones are 
numbered with Arabic numerals from zone 1 at the extreme north to zone 
38 on the Adriatic south of Scutari. The north-south rows of maps are called 
columns and the columns are numbered with Roman numerals from the 
Swiss border at the extreme west to the former Russian-Rumanian border 
at the extreme east. Each map bears two numbers together with the name 
of the principal town, e.g., "Zone 17, Kol. VIII, Hof Gastein." 

Relief is shown by means of hachures through which are drawn contours 
at 50 m. intervals. Elevations are plotted wherever measurements of any 
kind have been made and a special symbol shows not only how the eleva- 
tion was determined, but also whether the bench mark is on a church, wind- 
mill, house, etc., or is marked by a separate monument. 

Large waterbodies such as lakes, have parallel horizontally ruled shad- 
ing-lines, as on the French map. Large rivers and the shores of seas have 
black water-shading. Small rivers are single black lines. The vegetation 
symbols are minutely subdivided. Forest areas are covered with little 
circles. Rows of trees, groups of trees, single trees, large and conspicuous 
trees or tree groups, all have separate symbols, even to showing whether 
a tree has been trimmed into a definite shape by a gardener. In addition 
there are separate symbols for orchards and vegetable gardens, parks, 
underbrush, vineyards, hop gardens, rice fields and nine distinct symbols 
for varieties of wet, dry or sandy soil, swamp, etc. The culture symbols 
are almost numberless, including separate symbols for churches, mosques 
and synagogues, more than a dozen symbols for mills and industrial plants, 
six different symbols for railroads, fourteen for roads, ten for springs, wells 
and cisterns. As an example of this minute subdivision, the symbols for 
bridges show whether a railroad bridge is supported by stone, iron, or wooden 
piers, whether it can be crossed by infantry in close order, whether an extra 
track could be laid upon it in case of military need. Steep roads in the 
mountainous countries are crosshatched where their grade is 10% or more. 

This is, so far as the writer knows, the most elaborate map in the world. 
The blackfaced type of the lettering is a defect, and it is to be regretted that 



APPENDIX 145 

only one color has been used. But once the intricacies of the symbol system 
have been mastered, the wealth of information it gives, both to the student 
of land-forms and to the military officer, force the admission that it is one 
of the most remarkable maps ever made. 

Generalkarte der Osterreichisch-Ungarischen Monarchic 1 : 200 000. 

The sheets are bounded by parallels and meridians, longitude reckoned 
east from Ferro. Each map includes 1° of longitude by 1° of latitude, 
being thus just twice as wide from east to west and four times as long 
from north to south as a sheet of the Spezialkarte. These sheets are 
named after the principal town and also by the parallel and meridian which 
intersect at the center of the sheet, thus: "33° 45° Zengg," where 33° is the 
longitude and 45° latitude, and Zengg the principal town appearing on this 
sheet. 

Relief is expressed by means of brown hachures and elevations in meters 
above sea level, which are printed in black, with a symbol showing by what 
method the elevation was determined. All water bodies are blue, the 
large ones with water-shading. Buildings are black blocks, but not every 
separate building can be shown. Railroads are heavy black lines — the 
French symbol. Three qualities of roads are shown. Forests are green 
patches. The map is far inferior to the French map of the same scale, in 
detail, accuracy and execution. Like the French map it is an extremely 
useful summary of the general topography. Its large sheets present broad 
areas at a glance. 

ENGLAND 

The Ordnance Survey of England, Ireland, Scotland. See Fig. 5. 
See "Ordnance Survey Maps," by M. I. Newbigin, London. W. & A. K. 
Johnson, 1913. 

The Ordnance Survey has made a complete topographic map of the 
British Isles. This has been published in various editions and in scales of 
34, Yz*, 1 and 6 inches to the mile. The 1 inch is the most widely used and 
can be had mounted and also sectionally folded in book form. 

The sheets are rectangular and so are not oriented along true north and 
south lines. Each sheet is numbered and also bears the name of its prin- 
cipal town. In England the numbers begin at the northwesternmost sheet 
and run successively across the rows of sheets from W. to E. to map 152, 
the easternmost map of the southernmost row, see Fig. 1. The maps are 
not all perfectly aligned with each other; because of the extremely irregular 
shape of the British Isles, it has been convenient to chart some places along 
the coasts with maps whose greater dimension lies north and south, and other 
places with maps which overlap those inland. Most of the sheets cover 
areas about 27 miles from E. and W. by about 18 miles from N. and S. 
In Scotland the maps are numbered from the southwest corner eastward 
across successive rows to the northeasternmost corner, in 131 sheets, includ- 



146 APPENDIX 

ing the Shetland Islands. The standard size covers about 19 miles from 
N. and S. by 24 from E. and W., but some of the sheets are made larger than 
this in order that convenient units may be completed upon a single sheet. 
The map of Ireland is numbered like that of England. The number of 
sheets varies with each edition of the map. In one edition there are only 
sixteen sheets each over 60 inches wide. The most convenient edition has 
204 sheets, each sheet about 18 inches (18 miles) square. The different edi- 
tions vary not only in coloring, but in method showing relief, there being four 
different forms of the 1-inch map. On the most common form, relief is 
shown by both contours and hachures, the former in red with a varying 
interval, 50 feet near sea level, 100 feet up to elevations of 1000 feet and 
250 feet in the high hills. The contour elevation is printed in red upon every 
contour at its intersection with the edge of the map, and in black on the 
face of the map. The hachures are printed in a pinkish gray or brown. 
In the other editions shaded and unshaded contours are used; in one edition 
the layer system is employed. 

Large rivers and lakes have blue water-shading. On some of the sheets 
the sea appears in a plain blue color a little darker near the shores, with black 
contours to show the depth at 25-foot intervals down to 200 feet. Small 
rivers less than 15 feet wide are single blue lines. Canals are represented 
by double lines of blue. The symbols used are shown in Fig. 4. Buildings 
are shown in black with separate symbols for churches (with towers, with 
spire, or without either); for windmills, and for windpumps, and for light- 
houses, lightships and beacons along the shore. Metalled roads of first 
and second class are red, third class roads and unmetalled roads are black. 
Footpaths are single dotted lines. There are three symbols for railway, 
indicating double track, single, track and tram lines. Forests are shown 
by means of the small circles used on continental maps, over which a patch 
of bright green is printed. 

The map lacks much of the elaborate subdivisions of symbols seen on 
the continental maps. 

General Staff. The Geographic Section of the General Staff, War 
Office, publishes a large and varied selection of maps of British territories 
and other parts of the world in which Great Britain has special interests, 
such as Turkey, China, Persia, Arabia, Mesopotamia, South Africa, etc. 
A number of these form part of the International Map and are the best 
available maps of these sections. Many of these maps are described in an 
appendix to the latest English military "Manual of Map Reading and Field 
Sketching." 

BELGIUM 

The Belgian government has issued three series of maps. All employ 
contours, are printed in rectangular sheets numbered after the French 
system with longitude reckoned from Brussels. 

The most useful of these series is perhaps the 1 : 40 000 map. This is 



APPENDIX 147 

printed in one color, black, and each sheet covers 32 km. E. and W. by 20 
km. N. and S. The contour interval is 5 m. with a special hachured sym- 
bol for cliffs. Large water bodies are shown with water-shading. Woods, 
fields, parks, etc., are well classified and represented. 

The largest scale map, 1:20 000, has not yet been completed. It is 
similar to the 1 : 40 000, but is drawn in color with 1 m. contours, each fifth 
contour being emphasized. Towns and national roads are red, other roads 
black. Vegetation and land classification are shown by various colors. 
Sheets cover 8 km. E. and W. by 10 km. N. and S. 

The smallest scale map, 1 : 100 000 was republished with English legend 
during the war. 

LUXEMBOURG 

xnis area has been mapped in a series of 15 rectangular sheets each cov- 
ering 21 km. E. and W. by 17.2 km. N. and S. The scale is 1 : 50 000 and 
the maps are printed in colors, contours brown (elevations of contours not 
given), water features blue, woods spotted green with green shaded mar- 
gins, towns and roads red except rural roads and footpaths, which are shown 
in black. 

The German railroad symbol is employed, but only to distinguish between 
broad- and narrow-gauge lines, while the legend is given in French. 

HOLLAND 

Three important series of maps are issued by this country. All the 
sheets are bounded by parallels of latitude and meridians, with longitude 
based on Amsterdam, and the sheets numbered from west to east. 

The 1 : 50 000 map, which is complete in 62 sheets, is very useful. It is 
printed in black and employs hachures, well drawn and engraved. Each 
sheet covers about 44 by 27 km. Shoal water is shown by contours at 2.5, 
5 and 8 m. Vegetation symbols appear in large numbers and features of 
importance in this country, such as wet and dry ground, peat bogs, sand 
and sand dunes, are also clearly indicated. 

DENMARK 

The " Generalstabens Topografiske Kaart over Denmark" is in rec- 
tangular sheets with a scale of 1 : 40 000. Sheets are named, not numbered, 
and cover 18.4 km. E. and W. by 15.1 km. N. and S. The common edition 
is black, but there is another edition which uses blue for water, brown for 
national roads, and green for internal political boundaries. The black 
contours at 10 m. interval bear no elevations. Shallow water is lightly 
shaded; navigable channels, however, are shown with both contours and 
soundings. Vegetation is indicated by many symbols, but buildings are 
labeled instead of using a variety of symbols. 



148 APPENDIX 



NORWAY 

The " Topografisk Kart over Kongeriget Norge," scale 1 : 100 000, is 
divided into two parts. The S. half of the map, up to latitude 65° N., is 
in rectangular sheets, while the sheets of the N. part are bounded by parallels 
and meridians. 

The northern " Gradavdelingskart" is numbered in zones and columns — 
each E. W. zone bears a number and each N. S. column a letter, thus 
"Hammerfest, U3" — and covers 1° of longitude by 20' of latitude or 46 
by 37 km. The southern " Rektangelkart" is in sheets of about the same 
size with names, not numbers. 

Relief is shown by 30 m. contours in black without elevation numbers. 
One of the most interesting features is the contour shading which is based 
on the hachure system with the steepest slopes darkest and flat areas 
unshaded. Large water areas and swamps are colored blue, glaciers are 
shown in light green with dotted contours, forested areas are shown with 
circles for hardwood and stars for pines. Houses and roads are but slightly 
classified. 

SWEDEN 

The "Generalstaben Karta ofver Sverige," scale 1:100 000 is similar 
to the map of Norway in that the area is covered partly by rectangular 
sheets and partly by "gradblad" sheets bounded by meridians and parallels. 
The entire map comprises 110 sheets, the numbers begin with No. 1 at the 
S. W. corner of Sweden while the "gradblad" sheets start again with No. 1 
at the N. W. corner and end with No. 84. Longitude is reckoned from 
Stockholm. 

The map is a hachure map in black with water in blue. There is also an 
edition, scale of 1 : 200 000, with black contours. These contours are not 
numbered and are not continuous, being replaced in certain parts by 
hachures. Large rivers and lakes are in blue, small streams black, culti- 
vated land is shown by green and yellow areas. The forest symbols are 
like the Norwegian symbol. Railroads are shown as on the German maps. 
National roads are colored brown. 

SWITZERLAND 

This* is one of the best mapped areas of the world. The "Karte der 
Schweiz," 1:250 000 is a hachure map in black. The " Topographsche 
Karte," 1 : 100 000 is also a black hachure map. This map is complete in 
25 rectangular sheets with Roman numbers and about 70 by 48 km. Longi- 
tude is reckoned from Paris and 10' meridians and parallels are shown also 
on' a marginal subdivision in centigrads. The hachures are drawn darker on 
the S. E. slopes so give the effect of light and shade. Cliffs have a special 
symbol, rivers are blue, also glaciers, the latter with light "flow-lines." 
Forests are shown with the German symbol and culture symbols are similar 



APPENDIX 149 

also to the German. This is the survey carried out by Genl. Dufour and is 
commonly known as the Dufour map. 

The contour maps of the " Topographischer Atlas" are probably the 
best. The high Alpine areas are drawn 1 : 50 000 while the less rugged 
sections are 1 : 25 000. Each sheet of the Dufour map is divided into sixteen 
smaller sheets 17.5 by 12.0 km. for the former and these are called sections 
and are numbered. Each sheet of the latter covers a quarter of the 1 : 50 000 
and is lettered a, b, c or d. Longitude is based on Paris, and a marginal 
scale of latitude and longitude is shown; also a coordinate network of 6 cm. 
squares crosses every sheet. The origin of these squares is the observatory 
at Bern. 

Contours are printed in brown, those bearing the contour elevations 
being dotted. The interval is 30 m. for the 1 : 50 000 while the interval varies 
from 4 to 8 or 10 m. for the 1 : 25 000. Where contours cross glaciers they 
are shown in blue and on steep heights in black. Cliffs have a special black 
hachure symbol. Water is shown in blue with a different shade for ice. Most 
recent sheets also show depth contours in lakes. Forests are represented 
by the French symbol, while houses, churches, chapels and ruins have each 
their special sign, but labels are used to indicate other buildings as on the 
Danish maps. Three railroad symbols are used — normal, narrow and tram 
lines. Five kinds of road are distinguished, including foot and bridle paths. 
Gardens and parks are carefully indicated. 

These maps are of the highest grade and are said to be made from field 
surveys of the same scale. 

SPAIN 

The "Mapa Militar de Espana" in 345 sheets, scale 1: 100 000, is not as 
well drawn as the 1 : 50 000. It is colored with brown contours, green for- 
ests, and blue water. Madrid is used as the starting point for longitude 
and each sheet is bounded by meridians 1 grad apart and parallels 40 centi- 
grads apart. 

The 1 : 50 000 map is well engraved with 20 m. contours in brbwn, every 
contour numbered. Each sheet covers 23 km. by 18.6 km. Rivers are in 
blue, forests in green, also vineyards, gardens and orchards. Pasture land 
and farms are shown by a fine black line shading -symbol. The main roads 
are in red, others in black. A peculiar symbol, consisting of a heavy 
black line with light lines on the sides, is used for railroads. Only a few 
types of buildings are differentiated. 

PORTUGAL 

The "Carta de Portugal," 1:50 000, is in rectangular sheets numbered 
in zones from N. and S. and lettered in columns from W. to E. The longi- 
tude of Lisbon is used. Contours are in brown with 25 m. interval but 
unnumbered. Rivers are shown in blue; woods in green with separate 



150 APPENDIX 

symbols to show broad-leaved, pine and olive trees. National and city 
roads are in red, others in black. Railroads are shown in black, using the 
German symbol for double-track and French for single-track roads. 

There is also a map in thirty-seven rectangular sheets, 1: 100 000, num- 
bered like the French maps. It is similar to the above map, but is printed 
entirely in black. 

ITALY 

Italy publishes a "Carta d'ltalia," 1:100 000, in 277 sheets bounded 
by meridians and parallels and covering 30' longitude and 20' latitude 
(about 39.5 by 37.5 km.). Monte Mario Observatory, Rome, is used as the 
basis for longitude. Sheets are numbered like the French map from left to 
right across the system. 

There is an older edition in black with relief shown by hachures, crossed 
by 50 m. contours. The newer edition differs only in the use of color and 
substitution of shading for contours. The latter are shown in brown with 
hachure-like lines for cliffs. Gray shading is used on the S. E. slopes, although 
in some cases it has been applied where needed to bring out the form, rather 
than by rule. Contours are not always numbered, although on some sheets 
the elevation of every fifth contour is given. 

Water, ice and snow are shown in blue with "flow-lines" on glaciers. 
Near shore the sea depths are indicated by dotted contours at 5, 10 and 20 
m. but this is not done for the lakes. Vegetation is shown in green with 
separate symbols for dense and thinly forested areas, and for vineyards and 
meadows. Peat bogs are shown in blue. Five railroad symbols in black 
are used, including the " Telef erica." Roads are shown in red with 
symbols for varying width and for farm roads. Footpaths, mule paths and 
sheep trails are also indicated. A number of building symbols are shown 
in black. The most striking feature of the map is the relief, but the printing 
is inferior to that of most other national maps. 

THE BALKANS AND GREECE 

Some of the best maps of the Balkans have been prepared by outside 
nations interested in this" area. Austria has a "Karte des Balkanischen 
Halbinsels," 1 : 100 000, the sheets of which are bounded by parallels and 
meridians; and on some hachures are employed while brown or gray shad- 
ing is used on others. This map is difficult to obtain. 

Italy issued (1913) a map of Albania 1 : 500 000, with relief shown by 
S. E. shading and spot heights in meters. Sea contours at 50, 100, 200, 500 
and 1000 m. are also shown. 

France, in the middle of the last century, prepared a black hachure 
map of Greece, 1 : 100 000. 

Serbia has a 1 : 250 000 map in four colors with brown, 100 m. contours 
and gray S. E. shading-. Some sheets use the "layer system." Each sheet 
covers 1° longitude by 1° latitude (84 by 112 km.). Rivers, lakes and 



APPENDIX 151 

swamps are in blue; forests are shown by small green circles. Roads and 
railroads are few and hence very simply shown. There is also a map in 
four colors; scale 1: 75 000. It covers ninety-seven sheets. 

Roumania has a "Harta Militara a Romanici," 1: 100 000, in rectang- 
ular sheets. Sheets are numbered in zones from N. to S. and lettered in 
columns W. to E., thus "Bucuresch, Seria XII, Colonna H. Longitude is 
reckoned from Greenwich. 

Brown, 20 m. contours are used for relief, every one numbered. Water 
is shown in black. The German forest symbol is employed and the Austrian 
symbol for railroads. Telegraph lines are shown, as well as the usual 
buildings, churches, mills, crosses, etc. In some editions land-cultivation is 
shown in many colors with roads in red, brown and black. Roumania has 
also prepared mapsjn other scales including a "Harta Speciala," 1 : 50 000. 

Bulgaria has an unfinished map, begun in 1900, 1 : 50 000, in sheets 
bounded by parallels and meridians arranged in zones and columns like 
the Austrian map and covering 18.6 km. N. and S. by 20.5 km. E. and W. 
Brown, 20 m. contours are used, every fifth contour is heavy and is numbered 
on the map margin. Rivers are in blue, forests in solid green except on 
estates where black tree symbols are employed. Cultivated land is also indi- 
cated. Towns are in red, but isolated houses in black with Austrian symbols 
for church, synagogue and mosque. A 1 : 300 000 map is also published. 

Greece. A map, 1 : 75 000, with contours and shading has been partly 
completed. Sheets are bounded by parallels and meridians covering 30' 
longitude by 15' latitude (80 by 44 km.). Longitude is reckoned from 
Athens. Sheets are numbered in columns N. to S. and also named. 

The contours are in gray, each fifth contour emphasized. Water and 
swamps are in blue. The Austrian symbols for railroads, buildings, forests, 
springs and wells are used and the German for cultivated fields. Three 
qualities of road are shown in red. 

RUSSIA 

No one map has been issued covering the entire country and those pub- 
lished are inferior to other European maps. Only one will be described: 
The scale is 1 inch equals 5 versts or about 1 : 200 000. Longitude is counted 
from Greenwich, and sheets are rectangular with meridians and parallels 15' 
apart. Relief is shown by brown shading on the Norwegian plan, but is of 
inferior quality, and with few spot heights. Rivers are in black. Forested 
hills are in green, but black circle symbols are used for woods and orchards. 
Railroads are shown by the German symbol. Four classes of roads are 
shown. Churches and mosques are differentiated, but other buildings are 
simply massed into blocks. 

The other maps are in scales of 1 : 1 050 000, 1 : 500 000, 1 : 126 000, 
and 1 : 20 000, but none of these are believed to be complete. All are hachure 
maps except the last, which is a crude effort, apparently poorly surveyed and 
organized. 



152 APPENDIX 



ASIA 

For most of the continent, there are no regular surveys. Only a few 
reconnaissance maps, and such sheets as have been compiled and issued of the 
International Map, are available. The following descriptions are nol 
exhaustive, but include the most important maps. 

PALESTINE 

One of the best of many maps is the "Palestine Exploration Fund Map" 
— a reconnaisance map in rectangular sheets, 1 inch equals 1 mile. Sheets 
are numbered in Roman numerals from W to E. Each sheet covers 21.5 
miles E. W. by 32 miles N. S. Relief is shown by shading of the Italian 
type. Large water bodies are solid blue. Streams are blue lines and dry 
water courses a single black line. Towns are in red, and roads bl/ick. 
Orchards and forests are distinguished by different arrangements of a tree 
symbol. 

ASIA MINOR 

Richard Kiepert's "Karte von Kleinasien," 1:400 000, is the best 
general map of this region. It is in 24 rectangular sheets each covering 
244 km. E. W. by 184 km. N. S. Longitude is reckoned from Greenwich 
Sheets are arranged in lettered zones and numbered columns; thus 
" Cl, Smyrna." Relief is sketched in brown shading, or form-lines sug- 
gestive of contours. Lakes and seas are solid blue, rivers are black. Forests 
are not separately indicated, but fertile river basins are colored green. 
Roads, railroads, and town-locations are in black. 

Alfred Phillipson has prepared a " Topographische Karte des Weslichen 
Kleinasien," 1 : 300 000. It is a reconnaissance map based upon special 
surveys. Sheets are rectangular, covering 198 km. E. W. by 171 km. N. S. 
Longitude is reckoned from Greenwich. The sheets are numbered from W. 
to E. Relief is shown by brown 100 m. contours and brown shading of the 
Norwegian type. All water bodies are solid blue, the depths being indicated 
by contours and blue layer-shading. Vegetation is not shown. Roads 
and bridle-paths are in black, one symbol for each. The German symbols 
for railroad and industrial railway are plotted in black. Seven town symbols 
are employed, to indicate population. Ancient names are printed in red, 
the modern name in black. 

CAUCASUS 

The Caucasian Military Division has prepared a map of the Caucasus 
in 10 rectangular sheets, 1 inch equals 40 versts. The map is at best a 
rough reconnaissance. Brown shading indicates relief; water is blue; forests 
are green, and roads and towns black. 



APPENDIX 153 



PERSIA 



The Russians prepared a crude reconnaissance map, 1 : 840 000, and 
which is similar to the maps of Russia and Siberia. Brown Norwegian 
shading indicates relief, forests are green, rivers and roads black. 

The Mission Scientifique en Perse, under the guidance of J. de Morgan, 
prepared incomplete maps, on scales of 1 : 750 000 and 1 : 460 000 with 
black shaded relief, black rivers, green forests, and red roads. 

INDIA 

The Survey of India has prepared a map, scale 1 : 1 000 000. Sheets 
are bounded by parallels and meridians, 4 degrees each way; they are both 
named and numbered in columns from N. toward S. Longitude is reckoned 
from Greenwich. Relief is shown by contours, at intervals varying from 500 
to 2000 feet. 

Water bodies are solid blue. Vegetation is not shown, railroads are 
indicated by four symbols in black for double track, single track, meter 
gauge, and narrow gauge. Roads are in red, double lines or single lines. 

The 1-inch map (1 inch equals 1 mile) is bounded by latitude and longi- 
tude lines and covers 15 minutes each way. Longitude is reckoned from 
Greenwich. The numbers are those of the M° map, subdivided by means 
of minor numbers. Relief is shown by brown contours of 50-foot inter- 
vals, each fifth contour emphasized. The large streams are in blue, inter- 
mittent streams black. Dense forests, or jungles are shown by a darker 
green than open forest. In addition, an elaborate system of tree symbols 
is plotted in black. Three qualities of carriage road are shown in red ; even 
mile stones are plotted. There are symbols for camel-road, mule-path, and 
footpath. Five types of railroads are shown in black, and there is a special 
symbol for telegraph lines. All buildings are red. 

The 2-inch map (2 inches equals 1 mile), is an oriented map, the sheets 
covering 30 minutes each way. The relief is shown by brown contours with 
gray shading of the Italian type. The interval is 200 feet, each fifth contour 
emphasized. Relative heights such as the height of a river bank are given 
where these have military importance — thus . v 25 r means that the bank is 
25 feet above the river. Parts of rivers that contain permanent water are 
blue; those parts that are dry in the great droughts are black. Springs 
and wells are carefully marked. Large areas of cultivated land are yellow; 
forests are green. Roads and houses are indicated by a well-classified system 
of red symbols. 

SLAM 

Siam has been mapped by the Royal Survey Department of the Army of 
Bangkok, 1 : 50 000. The map is oriented, each sheet covering 10 feet 
each way. Longitude is reckoned from Greenwich. Water is shown by 



154 APPENDIX 

blue water-shading, and canals are carefully classified. There are contours 
or hachures; the relief being shown only by spot heights. A very elaborate 
system of vegetation symbols in green is used. Three qualities of roads are 
shown in red. Buildings are indicated by a variety of symbols. 
The entire legend of the map is printed in Siamese characters. 

INDO-CHINA 

The Service Geographique de lTndo-Chine has prepared a rectangular 
map on a scale of 1 : 100 000, covering 41.6 km. E. and W. by 50.4 km. 
N. and S. Longitude is reckoned from Paris. Sheets are named and 
numbered from W. toward E. Relief is shown by brown contours in 25 m. 
intervals, every fourth contour emphasized, but none of them numbered. 

All water bodies are blue, including swamps. The French forest symbol 
of circles and dots is plotted in green, together with green symbols for fruit 
culture, bamboo hedges, and other types of growth. 

Stone houses, pagodas, churches and forts are in red. Other houses are 
black. There are two qualities of road and one of railroad in black. 

CHINA 

There are only reconnaissance maps which cover but a part of this vast 
country. The following are among the most important. The Royal 
Prussian Land Survey prepared in the early 1900's; the "Karte von Ost- 
China,' ' in twelve sheets, scale 1 : 1 000 000, bounded by parallels and 
meridians and covering 6 degrees E. and W. by 4 degrees N. and S. Relief 
is shown by brown shading of the Norwegian type, with the few known 
elevations plotted in meters. Sheets are named, not numbered. Longitude 
is reckoned from Greenwich. Water bodies are blue, and salt water is a 
pale greenish blue. Vegetation is not shown. Towns of eight different 
sizes are shown, and there are special symbols for fort, camp, European 
P. O., Emperor's tombs, temples, churches, fortified harbors and harbors 
of open commerce. Two qualities of road are shown in red, and railroads 
building and planned and telegraph lines are plotted in black. 

The explorations of Dr. M. A. Stein under the direction of the Survey 
General of India, are mapped in sixty-nine sheets, 1 inch equals 4 miles. 
The maps cover the routes of journey in Turkestan and Kansu. Sheets 
are oriented, each covering 2° S. and W. by 1° N. and S. Longitude reckoned 
from Greenwich. Sheets are both named and numbered from N. toward S. 
as in the Indian Survey. Relief is in brown sketched hachures, of the Swiss 
shaded type — that is, the hachure lines are drawn darker on the N. W. slopes. 
All water bodies are blue, with special symbols for marsh and glaciers. 
The green vegetation symbols include jungle, grass and cultivated areas. 
Roads are in red, with special symbols for main road, camel-road, mule- 
path and footpath. Telegraph lines, forts, temples, sacred tombs, camps 
mines and frontier walls are all shown in black. Ancient and ruined build- 
ings, walls, etc., are in red. 



APPENDIX 155 

JAPAN 

The Imperial Geological Survey of Japan has prepared reconnaissance 
maps, 1 : 100 000 and 1 : 200 000. As they are similar in organization, 
symbols and design, the description of the larger map will suffice. The 
sheets are oriented, each covering 1° E. W. by 3 / 2° N. S. They are arranged 
in zones and columns, like the Austrian Spezialkarte. Thus the Fuji sheet 
showing the great volcano of Fujiyama, is called Zon 9 Col XI. Contours 
of 40 m. are printed in delicate gray, without numbers. All water bodies 
are light blue, with delicate water shading. Waterfalls, geysers, fumaroles, 
and five kinds of springs have each its special mark. Forests are not 
shown. There is a minute classification of building-symbols. The German 
symbol for railroad is used and a similar but lighter symbol indicates a rail- 
way under construction. Mines, quarries and prospects are classified under 
not less than forty-nine separate titles, each with its own symbol. The 
entire legend is in English. A new map, 1 : 25 000 is being prepared. 

DUTCH EAST INDIES 

The Dutch Island of Java has been mapped, 1 : 100 000. Each sheet 
covers 20 minutes each way, with longitude from Batavia. Relief is shown by 
50-m. brown contours. Water bodies are in solid blue, with names in blue. 
Forests are indicated by the green-circle tree-symbols. Agricultural lands 
are in two shades of solid green, and there are special symbols in black for 
a variety of native plants. The German railroad symbol is printed in black. 
Houses and three qualities of road are in red. In the lower margin of each 
sheet there are descriptions of the routes of telegraph and telephone lines. 

Larger maps, 1 : 50 000 and 1 : 20 000 are being prepared. Both are 
contoured with every tenth contour emphasized. 

SUMATRA 

The Topographische Inrichting has issued a map 1 : 25 000. Longi- 
tude reckoned from the middle meridian of Sumatra, 3° 15' west from Batavia, 
Java. The sheets of an old reconnaissance survey 1 : 100 000, were sub- 
divided each into sixteen lettered parts, which form the units of the present 
map. Every tenth contour of the brown 12-m. contours is emphasized, 
but none are numbered. Water bodies are blue, with names in blue. A 
well-classified system of plant-symbols is printed in black. Roads are in 
black, and the shapes of villages are plotted in solid green areas. 

AFRICA 

The Geographical Section of the British General Staff has prepared 
maps of Africa, 1 : 1 000 000, in the form of the International Map (see 
p. 165) which are largely compilations. Sheets cover 6° E. W. by 4° N. S. 
and are lettered in zones both N, and S, from the equator and numbered in 



156 APPENDIX 

columns W. to E. It is intended that this map shall ultimately summarize 
all the surveys of Africa, but as yet only a few sheets are issued, covering 
parts of Morocco, Tripoli, Egypt, Sudan, Somaliland, the region between 
Cape Verde and French Equatorial Africa, German S. W. Africa and part of 
Cape Colony. 

Relief is shown in brown contours, so far as it is known, and the contour 
interval varies according to the relief and available information. Many 
regions have only an indication of drainage, or at best of sketched, incomplete 
contours. Water bodies are blue, roads and trails are red. The sheets of 
the above map are each subdivided into twenty-four sheets, which are 
published on the scale of 1 : 250 000. They are called by a name and by 
the number of the 1 : 1 000 000 map, with a letter indicating the subdivision. 
These are reconnaissance maps, and represent a definite survey. Relief, 
roads, rivers, swamps, forest, farms, villages, telegraph lines, etc., are all 
sketched in black along lines of survey and exploration. This map, incom- 
plete as it is, is one of the best and most reliable sources of information 
available. . 

The Geographical Section of the General Staff publishes also a summary 
map, 1 : 2 000 000. Brown contours are drawn at 200 m., 500 m., and thence 
upward at 500-m. intervals. Rivers are blue. Forests are not shown. 
Railways are heavy solid black lines upon which are written the gauge of 
the railroad. Heavy broken lines are railroads under construction, and lines 
of slender open rectangles, indicate projected railroads. Other symbols 
are the same as those on the 1 : 1 000 000 map. The map takes especial 
care of boundaries, stating for each the date on which it was based. 

CAPE OF GOOD HOPE 

One of the most interesting maps of the 1 : 250 000 scale described above 
has been issued for this area. Relief is in brown 100 m. contours, and all 
contours are numbered, where the relief permits. There is a dotted sand 
dune symbol, which shows in what direction the dunes trend. All water 
bodies are blue, and, as is necessary in desert regions, wells, springs, pumps 
and pipe lines are carefully classified and plotted. Rivers which can be 
crossed by wheeled vehicles are dotted lines, so that solid lines indicate 
unfordable streams. The fords are shown in black. The circular tree 
symbol is printed in green for forested areas. Main roads are colored brown, 
wagon roads are either double or single dotted lines, and bridle-paths are 
finely dotted lines. The German symbol for R.R. is used. Villages and 
towns are black shaded areas, and isolated houses are small black dots. 

ALGERIA 

The French map, 1 : 50 000, is published in rectangular sheets covering 
38 km. E. E., by 20 km. N. S. and with longitude reckoned from Paris. 
Each sheet has a marginal kilometer scale entirely surrounding it. Relief 
is shown by brown contours, 10 m, interval, with light brown shading on 



APPENDIX 157 

S. E. slopes. Rivers are shown by blue shading, seas in light blue tint 
with contours. Forests are in green with special symbols for palms and 
olives. Buildings are shown in red as are also the four road symbols for good 
roads. Two other road symbols are in black. 

MOROCCO 

Several maps are available. The French reconnaissance map, scale 
1 : 500 000, is a rectangular map, covering the entire country with sketched 
contours in brown and water in blue. 

The French also prepared an incomplete sketch map in black, scale 
1 : 200 000. 

The Service Geographique de l'Armee has published a series of route- 
maps, covering in reconnaissance sketches certain lines of exploration, 
These show water in blue, and sketch form lines in black. 

There is a series of Spanish maps, irregular in size, scale and arrange- 
ment, to which space cannot be given in the present account. 

TUNIS 

A map is prepared by the Service Geographique de l'Armee, 1 : 50 000, 
and is identical in all respects with that of Algeria. 

TRIPOLI 

The Instituto Geographic© Militare has commenced two surveys, one 
on the scale of 1 : 100 000, the other 1 : 25 000. Both of these are at present 
incomplete. The sheets thus far issued are reconnaissance maps, covering 
small areas or routes of travel. In addition, a number of sketch maps of 
special areas have been prepared. The only map which covers the entire 
region is a very rough reconnaissance map, 1 : 400 000. Sheets are rectangu- 
lar, of variable size, with relief shown by sketched brown shading. Lakes 
are blue, all other data black. 

EGYPT 

The Carte Topographique de l'Egypte, prepared by the Expedition of 
Napoleon under the direction of Col. Jacotin, is a series of fifty-eight 
rectangular sheets, 80 km. E. W. by 50.8 km. N. S., covering the Valley 
of the Nile, and the southern part of the shore of Palestine. Longitude is 
reckoned from Paris. The map is a black hachure map, with topographic 
detail shown only along the Nile Valley. Villages and forts are shown as 
black blocks, and cultivated land by means of parallel dotted lines. The 
map is at best a reconnaissance, but is of especial historical interest. 

The English Survey Department of Egypt has prepared a map on the 
scale of 1 : 50 000. Sheets are named, and cover 15 minutes each way with 
longitude reckoned from Greenwich, All legend is printed in both English 



158 APPENDIX 

and Arabic. The map has contours of a very small interval, Yi m., anc 
every contour is marked with its elevation. Water bodies are blue, and th( 
complex canal system is expressed by means of a finely classified system o 
canal symbols. The vegetation, shown in green, is also minutely classified 
There are symbols for good carriage roads in red, for passable cart roads 
in black. Footpaths are single dotted lines. A system of abbreviations 
classifies the buildings, and these abbreviations are printed in both languages. 
Massed houses or villages are simply shaded areas. 

Another edition of this same map has an overprint in six colors, showing 
degrees of fertility of the soil. 

The Survey Department has also issued a map, covering the Nile Valley 
on the scale of 1 : 10 000. These maps bear the same numbers as the sheets 
of the 1 : 50 000 map, together with a number subdividing the larger map 
There! are no contours on the 1 : 10 000 sheet, but otherwise the two maps 
are very similar, save for the more minute classification of buildings and o 
vegetation on the larger scale maps. Cairo and Alexandria are separately 
mapped on the scale of 1 : 1 000. 

ABYSSINIA 

The Italians prepared a Schizzo del Teatro della guerra Italo Abissina, 
1 : 333 000, in one sheet, with relief shown by means of brown shading, 
water in blue and roads in red. 

ITALIAN SOMALILAND 

Two reconnaissance maps have been prepared, one 1 : 1 000 000, the other 
an incomplete map, 1 : 50 000. The former shows roughly sketched relief 
in brown hachures over a small part of its area. Rivers are blue, forests 
are light green, cultivated areas are yellow, minor woodlands white. Wagon 
roads and bridges are in red, trails are black dotted lines. 

The 1 : 50 000 map covers 10 minutes N. S. by 15 minutes E. W. Sheets 
are numbered and named. Contours are black, with 10 m. intervals. Water 
bodies are blue, wells and cisterns are recorded, and there is a symbol for 
termite ant-hills. There are also special symbols for stable dunes, mobile 
dunes and dry water-courses. There are five symbols for woods of different 
kinds of trees, and cultivated or prarie land is distinguished by a light yellow 
color. There are two road symbols, one for heavy and one for light traffic 
and a special sign for caravan routes. 

UGANDA 

The new map of Uganda, 1 : 250 000, is organized in accordance with the 
British General Staff system, which has been described above. The brown 
contours are at intervals of 200 feet; and where necessary dotted 100- 
feet contours are interpolated between them. A green tree-symbol of the 
German type is used for forests, and the denser the forest, the closer together 



APPENDIX 159 

are the tree-symbols spaced. Rivers are blue, and main roads are dark 
brown. One special feature is the printing of the explorer's descriptive 
notes upon the face of the map, thus: " Rocky, treeless hills," " Impene- 
trable forest," " no cultivation — long grass and bushes," " rapids," etc. 

FRENCH WEST AFRICA 

A rectangular reconnaissance map in four colors, 1 : 500 000, has been 
made. Sheets are named, and longitude is reckoned from Paris. Incomplete 
sketch-contours and a few elevations show relief along a few routes. 
Wells and water-courses are marked in blue, dry depressions in green, roads 
and camel routes in red. There are also reconnaissance maps on the scale of 
1 : 200 000, and for the Ivory Coast, 1 : 250 000. 

FRENCH EQUATORIAL AFRICA 

Only reconnaissance maps are available, showing detail along rivers 
and lines of exploration, 1 : 80 000 for the coast of French Congo, 1 : 200 000 
for the Chari region, and 1 : 500 000 for Ouadal. 

LIBERIA 

The best map of Liberia is the International map, 1 : 1 000 000. 

GOLD COAST 

The British General Staff has prepared a map, 1 : 1 000 000, showing 
water in blue and all other data in black, except for red boundary lines. 
Railways, road, telegraph lines and offices have special symbols. Relief is 
not shown. 

SIERRA LEONE 

The British General Staff has prepared a map of Sierra Leone, 
1 : 1 000 000, similar to that of the Gold Coast, except that the relief is 
roughly sketched in brown. 

PORTUGESE WEST AFRICA 

A map in one sheet of Portugese Guinea has been prepared, 1 : 500 000. 
The relief of part of the country is shown in sketched hachures of brown. 
Such of the water-courses as were known were sketched in blue. All other 
symbols are in black. 

There are special maps of some of the rivers. 

MUNI OR SPANISH GUINEA 

This area is covered by a rectangular map in four sheets, 1 : 400 000. 
Relief is shown by sketched brown shading. Rivers are blue. Culture is 
black. 



160 APPENDIX 



NIGERIA 



The British General Staff has prepared a map, 1 : 2 000 000, precisely 
like the 1 : 1 000 000 already described for the Gold Coast. 

There is also a reconnaissance map, 1 : 500 000, with sketched brown 
contours. 

GULF OF GUINEA 

The French Service G6ographique des Colonies has published a Carte de 
la Boucle du Niger, 1 : 500 000. It is a good summary reconnaissance in 
two sheets, extending from the mouth of the Niger westward through most of 
Liberia. Relief is shown by shading, rivers are blue, lines of communication 
red. 

CAMEROON 

The Germans during their occupancy prepared a reconnaissance map of 
this region in sheets of varying size, 1 : 300 000. The relief is shaded in 
brown, but some attempt at contours is made. All water bodies are blue. 
There is a symbol for villages, missions, market places and caverns. Roads 
have three symbols, railroads are shown by the German symbol, and tele- 
graph lines have the usual sign — a single thin line with small points pro- 
jecting from one side. 

BELGIAN CONGO 

The Belgian Secretaire General du Ministere des Colonies has prepared 
a map in fifteen sheets, 1 : 100 000. It is a rectangular reconnaissance map 
in black, showing hachured relief. Forests have the French symbol of in- 
terspersed circles and dots. The German symbol for railroad is used. The 
only special building symbols are a cross for missions, a black rectangle for 
market places, and small flags for army posts. 

MADAGASCAR 

The officers of the Infanterie de Marine have prepared an excellent 
survey of Diego Suarez, the northern part of Madagascar. There are 
sixteen rectangular sheets, 1 : 20 000, with 10-m. contours in brown, every 
fifth contour emphasized but none of them numbered. Streams are black, 
swamps and forests are indicated by the conventional French symbols in 
black. Four qualities of road, three of them for vehicles, are plotted. 

The Service Geographique du Corps d'Occupation has prepared a com- 
plete reconnaissance of the island in twenty-six sheets. The sheets are 
rectangular and vary in size. Relief is sketched in brown shading, water- 
bodies are blue, forested areas are green. Trails and roads, and the locations 
of villages, missions and army posts are in black. 



APPENDIX 1G1 



GERMAN EAST AFRICA 



tie 



A Karte von Deutsch-Ostafrika has been prepared, 1 : 300 000. Tl. 
sheets cover 2° E. W. by 30' N. S., longitude reckoned from Greenwich. 
The relief is in brown contours, with brown shading of the Norwegian type. 
Rivers are black lines, swamps are indicated by black horizontal dashes, 
but large lakes and seas are solid blue. Roads, trails and railroads are in 
black. 

I PORTUGUESE EAST AFRICA 

The Commissao de Cartographia has prepared a reconnaissance map, 
: 1 000 000. Relief is omitted from part of the map, but is lightly sketched 
m brown shaded contours, where data was available. Rivers and swamps 
are blue, and large water-bodies are light greenish-blue. Roads, trails and 
village locations are shown in black. 



NORTH AMERICA 

UNITED STATES 

See Price List 53. "Maps published by the Government of the United 
States." This list covers the maps of the various bureaus with directions 
for obtaining them. It may be secured from the Superintendent of Docu- 
ments, Washington, D. C. 

The Geological Survey is making a topographic map of the United States, 
(see Fig. 13), for which purpose the entire area is divided into rectangles, 
without reference to political divisions, but bounded by meridians and 
parallels of longitude. The areas are separately surveyed and mapped and 
issued in sheets usually about 18 by 20 inches in size, each designated by 
the name of a principal town or natural feature within the quadrangle. 
The scales used are 1 : 62,500, 1 : 125,000 and 1 : 250,000. The first (about 
1 mile to 1 inch) is used for the thickly settled or industrially important 
parts of the country, while the second (about 2 miles to 1 inch) is the most 
widely used. Contours are printed in brown with an interval varying 
from 10 to 200 feet, 20 being common and the interval being uniform for 
any one sheet. Hydrography is shown in blue and public works in black. 
(See Fig. 3.) Description of the scheme of the map and conventional signs 
are printed on the back of each sheet. About one-half of the country, 
including all of Massachusetts, Rhode Island, New Jersey and Connecticut 
is completed. Index maps giving names of sheets are published for each 
state or group of states. Single sheets are sold at ten cents each with reduc- 
tion for large quantities. Address The Director, U. S. Geological Survey, 
Washington, D. C. 



162 APPENDIX 



CANADA 



Sectional Map, 1 inch equals 3 miles. Bounded by parallels and merid- 
ians, covering %' E. and W. and y± N. and S. Sheets are named, and are 
numbered from W. toward E. The map is purely a reconnaissance survey, 
and many of the sheets are only partly completed. The relief is in black on 
some sheets, in brown on others, and is expressed by means of sketched 
contours, with light hachuring. Vegetation is not shown. Roads and trails 
are plotted in black and trails that have been surveyed are drawn as full 
lines. 

A " Sectional Map," 1 inch equals 6 miles, is issued by the Railway 
Lands Branch of the Department of the Interior. This map is bounded by 
parallels and meridians, and is like the Sectional Map described above. In 
addition to the sketched topography, there is plotted in color the classifica- 
tion and granting of lands. 

The Department of Militia and Defense has issued a series of sheets, 
which, when complete, will cover the frontiers of the Dominion, and lines 
of important navigation and communication, such as the St. Lawrence 
River. The maps are on the scales of 1 inch equals 2 miles; and 1 inch 
equals 1 mile. The sheets are bounded by parallels and meridians. The 
first map covers a degree E. W. by l /§° N. S. and the other, the sheets of 
which are of the same size, cover just \i this area. Sheets are both named 
and numbered. On the 1 inch equals 1 mile map relief is shown in brown 
25 -feet contours, every fifth contour emphasized and all contours numbered. 
Water-bodies are blue, and the larger ones are water-shaded. The forests 
are shown by means of a circular tree-symbol, printed in green. Metalled 
roads are colored brown, and two other qualities of road are shown in black. 
The American symbol for railway is used. Wooden houses are black, stone 
or brick houses are red, and letters are used to distinguish school, post 
office, blacksmith-shop and hotel. There are special symbols for churches, 
with and without spires, and for mills and factories. All of these are in 
black or red, to indicate wooden or stone structure. 

The Deparment of the Interior is preparing maps, some on the scale 
of 1 : 62 500 and others 1 : 63 360. Some of these sheets cover 15 minutes 
and in size match those of the United States, although the contour interval 
is usually a multiple of 25 feet instead of a multiple of 20 feet. Others 
are in large sheets, covering 45' E. and W. by 20' N. and S. These are 
all contour maps, and every fifth contour is emphasized. Water bodies 
are blue, and large lakes and rivers are solid blue areas. Vegetation is not 
indicated. Roads and trails are in red, though some of the maps show them 
in black. 

In addition, there are special large-scale maps of interesting regions, 
prepared by the Bureau of Mines, and small-scale maps of the unsurveyed 
parts, such as Newfoundland and the northeast. 






APPENDIX 163 



MEXICO 



Mexico has a map called the Carta de la Republica Mexicana, whose 
scale is 1 : 100 000. It is a rectangular map, covering about 53 km. E. W. 
by 40 km. N. S. The relief is in brown contours of 50 m. interval; none- are 
emphasized and none bear contour elevation. Perennial rivers are blue 
but intermittent streams are in brown. Roads and habitations are shown 
in red. The map is a rough reconnaissance sketch. 

There are other maps, on the scales of 1 : 200 000 and 1 : 500 000, 
1 : 1 000 000 and 1 : 2 000 000. 



SOUTH AMERICA 

The maps of South America are, for the most part, in a more or less 
chaotic state. Only organized survey maps of a large scale can be dealt 
with here and many small-scale, rough-sketch maps have been omitted. 

ARGENTINA 

The Instituto Geografico Militaire has issued a few sheets of a Carte 
Topografica de la Republica Argentina, 1 : 100 000. Each sheet covers 
30 minutes in both directions. Relief is shown by brown contours of 5-m. 
interval, with dotted auxiliary contours where necessary to express details 
of the relief. All water -bodies are blue. Vegetation is shown by a series 
of classified symbols. The German symbol for railroad is used for single- 
track roads and the Austrian symbol for double-track roads. Four different 
qualities of carriage roads are shown by symbols like those of the French. 
Telephone, telegraph and power lines have each a special symbol. Build- 
ings are minutely subdivided. 

The Estado Major del Ejercito is issuing an oriented map, 1 : 25 000, 
whose sheets cover 6 minutes each way. The brown 10-m. contours are 
plotted only upon the interfluves, but are wholly omitted from river valley 
floors. Each fifth contour is emphasized, but elevations are printed only 
at the margin of the map. All water bodies are blue. Vegetation is 
in green with pale green cultivated fields and the tree-symbol for forests. 
Roads are red, and are finely classified. All fences are plotted. Towns 
are brown and the buildings are black. 

BRAZIL 

In addition to some rough reconnaissance surveys, 1 : 650 000 and 
1 : 500 000, Brazil has a map prepared by the Commisao Geographica 
e Geologica de S. Paulo, 1 : 100 000. Sheets cover 30 minutes in both direc- 
tions. The brown contours have a 25-m. interval and every fifth contour 
is emphasized and numbered. All water-bodies are blue. Vegetation is 
; not shown. There are two road symbols. 



164 APPENDIX 



CHILE 



The Comision Chilena de Limites has prepared a boundary map in 
thirty-eight sheets of the Andean region, 1 : 250 000, so arranged as to 
include the eastern boundary line. The maps are not equal in size, and 
are not in alignment with each other from N. to S. Relief is indicated by 
brown shading of the Italian type, with the heights of peaks and other 
approximate elevations in meters. Water-bodies are blue, and the salars, 
or desert salt basins which occasionally fill with water, are blue dotted areas. 
Permanent lakes are water-shaded. Forested areas are green, towns and 
houses are red. The German symbol for railroads and one symbol each for 
roads and footpaths are plotted in black. 

The Oficina de Mensure de Tierras has prepared a map, scale 1 : 500 000, 
whose sheets are oriented, covering 2° 50' E. W. by 2° N. S. The relief is 
shown by crude brown shading, and plotted elevations in meters. Water 
bodies are in solid blue, and the salars are dotted, blue areas. The German 
railroad symbol indicates completed roads, those planned are heavy dotted 
lines. One symbol for road, and one for footpath are used. Each town is 
shown by a black symbol whose size is proportionate to its population. 

COLOMBIA 

An old and rough reconnaissance survey, 1 : 810 000, published during 
the middle of the last century is available. Each sheet contains the map 
of one state, so that the sheets do not fit together, edge to edge. Relief is 
shown by shaded black hachures, and the rivers and roads are in black. 



PERU 

There is a rough reconnaissance map called Mapa del Peru prepared by 
A. Raimonde, and published in Paris for the government of Peru. 

The map consists of thirty-three rectangular sheets, 1 : 500 000. Each 
sheet covers about 293 by 220 km. and bears a table of conventional signs 
in the margin, and each is entirely surrounded by graphic scales of latitude 
and longitude subdivided to minutes and graded to show longitude from 
Greenwich and also from Paris. Mountains are shown by brown shaded 
hachures of the Swiss type, but only great mountain chains are shown at all. 
Blue water-shading expresses the lakes and large rivers. Green irregular 
stippling indicates forests. The culture is in black, with special symbols 
for forts, tombs, missions, ruins, and several types of mines. Roads are single 
lines, railroads double lines, and projected railroads are dotted lines. 

Peru has also a very crude map, 1 : 1 000 000, with sketched brown shad- 
ing to show relief. Its one advantage is that the names of nearly all rivers, 
including fairly small tributaries, are given. Forests are green and roads 
are shown in red. 



APPENDIX 165 



CENTRAL AMERICA 

The writer is not aware of any large-scale surveys of Guatemala, Hon- 
duras, San Salvador, Costa Rica, or Nicaragua. There are as yet only small 
scale sheets of each country as a whole, together with special surveys of a 
few important districts. In Nicaragua, reconnaissance surveys along the 
proposed route of the canal have been made. 

PANAMA 

The Ishmian Canal Commission has prepared and published a hydro- 
graphic map covering the canal and a few kilometers on each side of it, 
1 : 40 000. The contours are sketched in black. Large water-bodies are 
solid blue, all others are black. There are special symbols for swamp and 
forest, both in black. In addition there is an elaborate system of hydro- 
graphic symbols showing buoys, lights, etc., and depth of water is shown by 
means of contours and soundings. 

WEST INDIES 

Lieut. Col. Glenn Smith, U. S. A., is now engaged in mapping the Domi- 
nican Republic and it is understood that his work will also include Haiti 
and probably some of the other islands. 

CUBA 

The old Richardo map, called " Isle de Cuba, Carta Geotopografica," 
1 : 200 000, seems to have been made about 1875. Relief is expressed by 
black hachures. The entire map is in black, with black water-shading. 

During the American Military occupation, reconnaissance maps were 
made, which remain to-day the best maps possessed by the island. 



THE INTERNATIONAL MAP OF THE WORLD 
See " Maps and Survey " By Hinks 

It will be obvious from the above descriptions of the various government 
maps that some uniform scale, size of sheets, and system of symbols is very 
desirable. It was proposed at the International Geographical Congress 
in Berne in 1891 that an international map of the world be published on 
the scale of 1 : 1 000 000 in sheets of uniform size and shape, systematically 
arranged, and drawn in uniform style. Little was done for a number of 
years. The question was revived at the Congress of 1908 and finally the 
British Government called a meeting of the principal governments of the 
world in 1909 and all details and plans were agreed upon. These included 
a uniform set of symbols and conventional signs, with water features in 



166 APPENDIX 

blue, roads red, and railroads black. Contours are in brown with a usual 
interval of 100 m. and tinted on the layer system, following the spectrum 
order of colors. The sheets cover an area of 4° in latitude and 6° in longi- 
tude, based on Greenwich. Only a small number of sheets have been pub- 
lished and these are not uniform in their contour coloring and interval 
with the adopted standard. A number of these maps have been published 
by the British General Staff since the war began. These are noted under 
Great Britain. 



2. SUGGESTIONS FOR A COURSE IN MAP READING 
AND SKETCH MAPPING 

In an article in the Infantry Journal * Major C. D. Herron points out 
several important points in connection with "Map Reading." To begin 
with the instructor must know the subject himself and know how to make 
it clear to a student. As Major Herron says " When the mind of the instructor 
is muddy, the pupil is lost." Again, "It is especially to be borne in mind 
by instructors that all extraneous matter must be avoided." There are 
so many interesting applications of map reading that the instructor must 
continually restrain himself from introducing more of these features than 
is necessary to show the usefulness of the work and keep up the students' 
interest. 

As Major Herron also points out it is just as absurd to say that "the 
way to learn to read a map is to make one," as it is to say that "to read 
the English language one must first write it." Map reading is the best 
possible approach to map making, and in giving the former all extraneous 
matter in reference to map making should be avoided just as all matter 
in regard to transits, levels, plane tables, etc., should be avoided until the 
student has finished sketch mapping and understands thoroughly the 
fundamental principles of the work and the use of the simpler instruments. 

A course on map reading to be effective must not be a lecture course. 
Students should be required to study the text and should be assisted where 
additional explanation is necessary, but they should use almost their entire 
time in answering questions and working out problems from maps. Lecture 
courses are popular — students like to have matter presented to them in 
a simple, easily understood form — but this form of instruction will not pro- 
duce one man who can really use a map. Each article in the text is fol- 
lowed by a number of questions, which will suggest others to an alert 
instructor, and each student should be required to answer all these ques- 
tions by himself, and his work should be marked and returned for correction. 

In sketch mapping the same division of time is essential for anything 

like proficiency. Students cannot learn to make maps by lectures or in 

the class room. Actual practice in the field is the only way to master this 

art. Furthermore, time must be available so that the men can be required 

* " Instructing in Map Reading," May, 1917. 



APPENDIX 167 

to produce good results. The student should understand in the beginning 
that incomplete, careless or inaccurate work will not be accepted. Maps 
must be complete with title, scale, etc., and can only be made by patient 
and careful labor. Strive first for results, then explain the meaning of 
efficiency and try to get speed. 

Equipment 

An attempt has been made in Map Reading to give all essential data 
for exercises in the text. It is desirable to have a small collection of U. S. 
G. S. maps, which can be easily and cheaply secured, and also a few examples 
of some of the foreign maps such as the English, French and German, as 
well as two or three of the International Maps. The Army Service Schools 
at Fort Leavenworth also publish the Hunterstown sheet in the scale of 
12 inches equals 1 mile and this map is useful for class-room explanation. 
Certain sheets of the U. S. G. S. showing special features are mentioned 
in the text. 

In connection with contours it has been found that sketching contours 
from simple models is an excellent exercise. The half tones in the text are 
not as good for this purpose as the actual models themselves. These can be 
modeled in clay and cast in plaster or may be secured from Mr. Walter 
E. Rich of 135 DeKalb Avenue, Brooklyn, New York. 

For Sketch Mapping the sketch case equipment is necessary. These 
cases can be made up at a total expense of about $8 each, complete. The 
20-inch hard-fibre carrying case can be purchased in a trunk store at about 
$3. A standard No. 2| camera tripod can be bought for about $2.25 and 
a special plate, which is set into a drawing board and held by screws, serves 
to fasten the board to the tripod. These plates can be made by any mechanic 
or bought from a camera dealer. Two 12 by 17 incli drawing boards will 
cost about $1.50 and one will serve for the sketch board and the other for 
a slope board. Suitable paper, 11 by 16, pencils, erasers, thumb tacks, 
etc., complete the outfit with the exception of the sighting scale. This 
latter may be purchased from the Army Service Schools or can be made 
by a carpenter. It should be made of hard wood, such as maple, triangular, 
about 8 inches long and with faces f-inch wide. A |-inch hole should be 
bored lengthwise through the scale (can be done in a lathe) and filled with 
lead. The reading scale and scales of paces are drawn on paper and glued 
to the scale. 

The slope board is made by boring a small hole at the center of one end. 
A 2- or 3-oz. lead weight is fastened to a piece of fine linen cord about 2 
feet long and one end is passed through this hole and knotted. A line is 
drawn at right angle to the top edge of the board marking the zero of the 
scale. The scale can be conveniently drawn at the bottom edge of the 
board 16 inches from the hole and graduated by degrees up to 20° each way 
from the zero line. The graduations are best laid out on a line parallel to 
the top edge. The distances out to the degree marks in inches will be 0.28, 



168 APPENDIX 

0.56, 0.84, 1.12, 1.40, 1.68, 1.96, 2.25, 2.53, 2.82, 3.11, 3.40, 3.69, 3.98, 4.28, 
4.58, 4.89, 5.19, 5.50 and 5.82. The slope diagram, Fig. 70, can be used foi 
reductions, although it is preferable to have a larger scale diagram pasted oi 
the back of the slope board and shellacked for protection. 

Sketch pads for Landscape Sketching can be made by almost any print- 
ing establishment. Fifty sheets to a pad is a convenient number. A sketch- 
ing screen should also be available. This can be made by a carpenter oui 
of narrow strips of |-inch wood. The frame should be 6 by 9 inches (inside 
dimensions). Ordinary white cord fastened with tacks can be used for th< 
lines. The bar is 20 inches long, and the peep sight, secured to a 3-inch 
upright, simply a piece of tin with a small hole in it. 



3. BIBLIOGRAPHY 

Map Reading 

y 1. "Military Map Reading." By Capt. C. O. Sherrill, U. S. A. Agents: 
U. S. Cavalry Association. Ft. Leavenworth, Kansas. A standard 
text widely used in the Army. 
2. "Military Topography." By Capt. Chas. B. Hagadorn. U. S. Military 
Academy Press, West Point, N. Y. Part I: Map Reading, Part II: 
Map Making. 1908. 280 pp. Especially complete in figures, plates 
and illustrations, including a comparison of the conventional signs 
used on the principal government maps of the world. 

\ 3. "Map Reading and Topographical Sketching." By Edwin R. Stuart, 
U. S. M. A. New York. McGraw-Hill Book Co. 1918. 140 pp. 
A new and up-to-date treatment of the subject in a short, concise form. 

0( 4. "Military Maps Explained." By Capt. H. E. Eames. Kansas City, 
Mo. Franklin Hudson Pub. Co. 1909. 143 pp. Covers the usual 
field of map reading. 

5. "Military Map Reading." By Major Wm. D. Beach, Kansas City, Mo. 
Franklin Hudson Publishing Co. 1912. 86 pp. A very elementary 
treatment. 
J 6. "Military Topography and Photography." By Floyd D. Carlock, 
IT. S. A. Menasha, Wis. George Banta Pub. Co. 1916. Deals with 
map reading and mapping by plane surveying methods. 

^ 7. "Map Reading and Panorama Sketching." By an Instructor. London. 
Sifton, Praed & Co. 1917. 144 pp. Contours are carefully explained 
with excellent figures. Panorama sketching and map sketching by eye 
are also discussed. 
:j 8. "Maps and Survey." By Arthur R. Hinks. Cambridge. The Uni- 
versity Press. 1913. 206 pp. Covers map anah^sis based largely on 
the Ordnance Survey and International Maps. Covers the use of the 
compass and plane table, route sketching, etc. 



oc 



APPENDIX 169 

9. "Maps: How They are Made; and How to Read Them." By H. N. 
Dickson. London. G. W. Bacon & Co. 1912. 68 pp. Brief treat- 
ment, somewhat elementary in its character. 

10. "Contours and Maps." By Frederick Morrow. London. Meikle- 
john & Son. 1913. 120 pp. Deals mainly with the use of ordnance 
maps and gives several examples of "oroscopic" maps. 

11. "Ordnance Survey Maps." By Marion I. Newbigin. London. W. & 

A. K. Johnston. 1913. 130 pp. Meaning and use with illustrations. 

12. "Map Work." By Bryant and Hughes. Clarendon Press, Oxford, 
Eng. An excellent work which also includes the elements of surveying. 

13. "The Military Map." Translated from the Elements of Modern 
Topography of the French School of War. London. Macmillan & 
Co. 1916. And second volume of "Additional Chapters" covering 
geology and contours. 

14. "Aids to the use of maps employed by the English, French, Belgian 
and German Armies." By Thos. Drew. London. Jarrold & Sons. 

. £ 1917. 85 pp. An excellent little book covering largely the differences 

in methods of representation, signs, abbreviations, etc. 

15. "DasKartenlesen." By Gabriel Tambri. Imsbruck, Heinrich Schwick. 

1912. Gives the Austrian conventional signs with examples, etc. 

16. " Kartenkunde," by Dr. M. Groll. G. J. Goschen Verlagshundlung, 
Berlin, 1912. 2 Vols. Covers the history of map making, map read- 
ing, projection, etc. 

Map Making 

See also 2, 3, 6, 8, 12 

<\ 17. "Military Sketching and Map Reading." By Capt. L. C. Grieves. 

U. S. Infantry Association. Washington, D. C. 1917. 95 pp. A brief 

well-known and widely used text. 
>X 18. "Elements of Military Sketching and Map Reading." By Capt. John 

B. Barnes. New York. D. Van Nostrand Co. 1917. 100 pp. A 
brief text also widely used. 

19. "Military Sketching made Easy and Military Maps Explained." By 
Col. H. D. Hutchinson. London. Gale & Polden. 230 pp. Covers 
map reading, instruments for mapping and panorama sketching. The 
map making portion deals with the instruments used in ordinary sur- 
veying. 

20. "Military Sketching and Map Reading for N. C. O.'s and Men." By 
Major R. F. Legge. London. Gale & Polden. A brief treatment 
of fundamental principles. 

j/ 21. "Military Sketching, Map Reading and Reconnaissance." By Lieut. 
Col. A. F. Mockles-Ferryman. London. Edward Stanford. 1911. 
200 pp. An excellent and complete treatment. 



J 



170 APPENDIX 

22. "Topographical Drawing and Sketching." Including application of 
Photography. By Major Henry A. Reed, U. S. A. New York. John 
Wiley & Sons. 1912. 210 pp. Deals largely with the more advanced 
features of topographical sketching and mapping. 

Landscape Sketching 

See also 3, 7, 15, 17 

23. "Military Panorama Drawing." By Major R. F. Pearson. London. 

Gale & Polden. 1914. In three lessons with notes on Panorama draw- 
ing from maps and mapping from panorama drawings. 20 pp. 

Geology and Maps 

See also 13 

^ 24. "Interpretation of Topographic Maps." By Salisbury and Atwood. 
Professional Paper No. 60. U. S. G. S. 1918. 84 pp. and 151 maps. 
A wonderful collection selected from the maps of the U. S. G. S., show- 
ing examples of various types of topography and their relation to 
geological form and physiography. 
25. "Military Geology and Topography." Edited by Prof. H. E. Gregory. 
New Haven. Yale University Press. 1918. 280 pp. Deals with the 
geological problems in connection with military work and the study 
of these problems as illustrated by maps. Also covers map reading. 
\ 26. "Geological and Topographical Maps, their Interpretation and Use." 
By A. R. Dwerryhouse. London. Edward Arnold. 1911. Deak 
principally with the relation of topography as shown by maps to rock 
structure. 



INDEX 



A 

Abbreviations, French map 

Abyssinia, maps of 

Accuracy of contours 

pacing 

scaled distances 

traverses 

Adjustment, of traverses 

Africa, maps of 

— , French West, maps of 

— , Equatorial, maps of 

— , German East, maps of 

— , Portugese East, maps of 

— , — West, maps of 

— , South, maps of 

Algeria, maps of 

Alidade, 

— , construction 

— , use 100, 

America, Central, maps of 

— , North, maps of 

— , South, maps of 

Angle, horizontal 

— , measurements 39, 90, 

— , slope 

— , vertical 59, 94, 

Argentina, maps of 

Arrow, see Direction. 

Asia Minor, maps of 

Austria-Hungary, maps of 

Azimuth 

B 

Balkans, maps of 

Belgium, maps of 

Bench marks 

Bibliography 

Big Dipper 

Board, slope 118, 

Brazil, maps of . . . . 

Buildings, signs for 10, 15 

Bulgaria, maps of 



17 
158 

30 

94 

48 
101 
102 
155 
159 
159 
161 
161 
159 
156 
156 

96 
167 
123 
165 
161 
163 

96 
118 

55 
118 
163 

152 

144 

39 



150 
146 
8 
168 
37 
167 
163 
, 86 
151 



c 

Cameroon, maps of 160 

Canada, maps of 162 

Cape of Good Hope, maps of 156 

Carte de France 140 

, conventional signs 16 

, editions, etc 140 

, relief 19, 35 

, scale 43 

■-, sheets of 5 

Case, sketch 81, 96 

Caucasus, maps of 152 

Characteristics 5 

Chile, maps of 164 

China, maps of 154 

— , Indo-, maps of 154 

Churches, signs for 17 

Coll 25 

Colombia, maps of 164 

Colors used on maps. . . .7, 10, 11, 15, 32 

Compass, instrument 36 

— , mariner's 39 

— , points of 39 

— , surveyor's 40 

Congo, maps of 159 

— , Belgian, maps of 160 

Contours, accuracy of 30 

— , datum for 21 

— , definition of 19 

— , depression 28 

— , elevation of, 21, 23, 28, 113 

— , estimating heights from 28 

— , between 29 

— , form of. 19, 25 

— , interval 21, 44 

— , interpolation of Ill, 124 

— , principles of 23 

— , relation to scale 44 

— , underf eatures 30 

Conventional signs, see Signs. 

Coordinates 72 

Crests, location from contours 63 



171 



172 



INDEX 



Crests, military 62 

— , topographic 62 

Cuba, maps of 165 

Curvature of earth 65 

D 

Datum 21 

Declination 36 

Deflection 136 

Delineations 127 

Denmark, maps of 147 

Depression contours 28 

Descriptions by coordinates 72 

grid system 72 

letters and numbers 10 

— of National Maps 139 

— of targets 136 

Details, location of 103 

Diagram, slope 120 

Difference in elevation, 94 

, measurement of 118 

Direction, from maps 41 

— marks 2, 36 

— , methods of obtaining 37 

— , stating 39 

Distance, accuracy of scaled 49 

— , effect in sketching 127 

— , estimating 77 

— , horizontal 94 

— , inclined 94 

— , measurement of 93 

— , plotting by 90 

— , vertical 94 

Divide 25 

Drafting 85 

Drainage 25, 111 

Dutch East Indies, maps of 155 

E 

Earth's curvature 65 

East Indies, Dutch, maps of 155 

Egypt, maps of 157 

Elevation difference in 94, 123 

— from contours 28 

— , methods of determining . 118 

— of contours 21 

Embankments, signs for 10, 11, 86 

— , slopes of 56 

England, maps of 145 

English Grid System 72 

Enlargement 87 



Equipment for mapping. 167 

Error of closure 101 

Exaggeration of vertical scale 54, 135 

F 

Fences, signs for 11, 16, 86 

Fords, signs for 10 

Fraction, representative 42 

France, maps of 140 

— , Carte de, see Carte. 

French Coordinate System 74 

G 

Geology, bibliography 170 

— , relation to topography 2 

German maps, conventional signs. . . 7 

, relief 19 

, scale . 44 

Germany, maps of 142 

Gettysburg- Antietam Map 10 

Gold Coast, maps of 159 

Good Hope, Cape of, maps of 156 

Graphical scale 48 

, construction of 46 

, use in mapping 120 

Greece, maps of 151 

Grid system 72 

Guide lines for lettering 84 

Guinea, Gulf of, maps of 160 

— , Portuguese, maps of 159 

— , Spanish, maps of 159 

Gulf of Guinea, maps of 160 

H 

Hachures 18 

Holland, maps of 147 

Hungary, maps of 144 

Hunterstown map 10 

I 

India, maps of 153 

Indies, West, maps of 165 

— , Dutch East, maps of 155 

Index maps 5 

Indo-China, maps of 154 

Instructions for study 166 

International map 165 

, boundaries of 3 

, layer system used on 32 

Interpolation of contours Ill 

Intersection method 103 

Interval, contour 21 



INDEX 



173 



Interval, relation to accuracy 30 

— , — scale 44 

— used on maps 44 

— , vertical, see Contour Interval. 

Intervisibility, effect of trees , 66 

— , of stations 64 

— , towers for 65 

Ireland, maps of 145 

Italy, maps of 150 

Ivory Coast, maps of 159 

J 

Japan, maps of 155 

Japanese maps 19 

K 

Knolls 25 

L 

Landscape sketching, see Sketching, 
Landscape. 

Layer System 31 

Lettering, freehand, 83 

— on maps 7, 10, 15 

Leveling 116 

Liberia, maps of 159 

Line, of sight 64 

— , boundary 17 

Lines, ridge Ill 

— , guide 84 

Location, of details 103 

— on maps 76 

— , see also Descriptions. 

Longitude, origin for 3 

— , meridians and 36 

Luxembourg, maps of 147 

M 

Madagascar, maps of 160 

Mapping, bibliography 169 

— , contour Ill, 122 

— , details 103 

— , flat 90 

— , methods 90 

— , Road 105 

— , sketch xi, 167 

Map, distance, see Slope Scale, 

— , Hunterstown 10 

— , Reading x, 166 

, bibliography 168 

Maps, boundaries of 3 

— , cost of 7 

— , definition ix 



Maps, editions of 6, 7, 11 

essential features of 2 

field use 76 

history of 6, 139 

index 5 

kinds of ix 

large scale ix, 10 

orienting 37 

revisions, 6, 7 

sheets 3, 5 

signs, see Signs, Conventional. 

military ix, 2 

— , importance of revision 6 

— , scales used 43, 61 

— , use 2, 81 

national (see also name of map or 

country) x, 139 

Topographic, definition 1 

— , field use 76 

— , use 1, 2 

U. S. G. S 161 

, boundaries of sheets. 3 

, conventional signs . . 8 

, contours 28 

; , number of sheets ... 5 

, relief 19 

, roads on 7 

, scales 46 

, vegetation on 7 

Ordnance 145 

, conventional signs 11 

, editions 11 

, number of sheets 5 

, relief 19 

— , War Game 10 

Marginal Information 3 

Measurements of angles, see Angles. 

— of distance 93 

Meridian 3, 36, 37 

Metric system 44 

Mexico, maps of 163 

Mil system 136 

Military crest 62 

Models for contours 22, 167 

Morocco, maps of 157 

Muni, maps of 159 

N 

Name of map sheets 3 

Nigeria, map of . 160 

Normal scales 61 



174 



INDEX 



North Star 37 

Norway, maps of 148 

Norwegian maps, relief on 19 

, shading 35 

O 

Offsets s . 103 

Ordnance survey, see Maps, Ordnance. 
Orienting a map 37, 76 

— the sketch board 99, 106, 107 

Oroscopic Method 34 

P 

Paces, scale of 95 

Pacing 93 

Pad, sketch 133, 168 

Palestine, maps of 152 

Panama, maps of 165 

Panoramic sketching, see Sketching, 
Landscape. 

Persia, maps of 153 

Perspective 129 

Peru, maps of 164 

Physiography 2 

Plotting ,90, 91, 103 

Point, reference 135 

— , vanishing 131 

Points, controlling Ill 

— of compass 39 

Pointer, see Direction. 

Polaris 37 

Poles, sighting 100 

Portugal, maps of 149 

Position sketching 98, 106 

Practicable Slopes, Table of 57 

Principles of contours 23 

Profile paper 54 

Profiles, construction of 53 

— , definition of 52 

— , scales for 54 

Projection 3 

R 

Radiation method, for details 103 

Railroads, signs for. . 11, 17, 86 

Range 136 

Ranges for artillery, etc 50 

Reading Scale 46 

, construction of 48 

, use in mapping 120 

Reduction 87 



Relief 

— , accuracy 1 

— , drainage and 25, 11 

— , hachures for 1: 

— , layer system for 3 

— , map or model 3 

— , methods of showing 18 

— , oroscopic method 34 

— , requirements for showing 18 

— , ridge lines and 25 

— , shading and 35 

— , spot heights for 19 

— , visualizing 18, 27, 31, 61 

See also Contours. 

Representative fraction 42 

Resection, for location 78 

— , for mapping 108 

Ridge lines, and drainage 25 

, in contouring 113 

Road mapping 105 

Roads, signs for 7, 11, 17 

Roumania, maps of 151 

Russia, maps of . . . 151 



Saddles 25 

Scale 2 

— , engineer's 48 

— , equivalent 43 

— for profiles 54 

— , graphical 46 

— , map distance 59 

— , methods of stating 42 

— , mil 136 

— , normal 61 

— , reading 46 

— , relation of detail to 7, 44 

— used for maps 44 

Scaling, accuracy 48 

— , distances from maps 46 

Scotland, maps of 145 

Screen, sketching 131 

Sections 51 

Serbia, maps of 150 

Set-up ....100, 123 

Siam, maps of 153 

Sierra Leone, maps of 159 

Sighting, with alidade 100 

Signal stations, visibility 62 

Signs, conventional 2 

— for buildings 10, 15, 86 






INDEX 



175 



Signs for churches 17, 8G 

embankments 10, 1 1 , 86 

fords 10 

large scale maps 10 

railroads 11, 17, 8G 

roads 7, 11, 17, 86 

sketch maps 86 

windmills 17 

— , number and kinds 7 

— , of Carte de France 15 

— , of Ordnance survey 11 

— of U. S. G. S 7,8 

— of U. S. Geographic Board 8, 86 

— , relation to detail and scale,. . .7, 8, 86 

— , use of colors 7, 10, 11, 15, 32 

— , use of lettering 7, 10, 15 

See also Descriptions of National 

Maps 139 

Sketch, board 167 

— case .^ 81, 96 

— from contour map 69 

— mapping xi, 167 

— pads 133, 168 

Sketching, landscape x 

, bibliography 170 

, delineations for 127 

— — , effect of distance in 127 

from contour maps 69 

, perspective in 129 

, steps in 125, 132 

, use of 125 

, vanishing point in 131 

with sketch pad 135 

with sketching screen 132 

— , panoramic, see Landscape. 

— , position 98, 106 

— , screen 131 

Slope angle 55 

— board 118, 167 

— diagram 120 

— fraction 55 

— ratio 55 

— scale 59 

Slopes, changing 56 

— from contours 58 

— , methods of stating 55 

— of embankments 55 

— , practicable 57 

Somaliland, maps of 158 



Spain, maps of 149 

Spot, heights 1 <) 

— levels l!) 

Squares, method of 87 

Streams, contours at 27 

— , signs for 10, 15, 86 

Sumatra, maps of 155 

Surveying, 81, 90 

Surveyor's compass 40 

Sweden, maps of 148 

Switzerland, maps of 148 

T 

Target 136 

Three-point method 108 

Title 2, 3 

Topographers 82 

Topographic crest 02 

Towers, necessary height of 65 

Tracing, paper method 109 

Traversing method 91, 98 

— road 98 

Triangulation method 92 

for position sketching 10(> 

— stations 8 

Tripoli, maps of 157 

Tunis, maps of 157 

U 

Uganda, maps of 158 

Underf eatures 30 

United States, maps of 161 

U. S. G. S. Maps, see M\ps U. S. G. S. 
U. S. Geographic Board 8, 86 

V 

Vanishing point 181 

Vegetation 7 

Vertical Interval, see Interval, Con- 
tour. 

Visibility, of areas 66 

See also Intervisibility. 

W 

Wales, maps of 145 

Water features 10, 15 

Watershed 25 

West Indies, maps of 16fi 

Windmills, signs for 17 



CIVIL ENGINEERING— Continued 
5e Highways; Municipal Engineering; Sanitary Engineering; 
Water Supply. Forestry. Horticulture, Botany and 
Landscape Gardening. 



6 — Design. Decoration. Drawing: General; Descriptive 
Geometry; Kinematics; Mechanical. 

ELECTRICAL ENGINEERING— PHYSICS 
7 — General and Unclassified; Batteries; Central Station Practice; 
Distribution and Transmission; Dynamo-Electro Machinery; 
Electro-Chemistry and Metallurgy; Measuring Instruments 
and Miscellaneous Apparatus. 



8 — Astronomy. Meteorology. Explosives. Marine and 
Naval Engineering. Military. Miscellaneous Books. 

MATHEMATICS 
9 — General; Algebra; Analytic and Plane Geometry; Calculus; 
Trigonometry; Vector Analysis. 

MECHANICAL ENGINEERING 
10a General and Unclassified; Foundry Practice; Shop Practice. 
10b Gas Power and Internal Combustion Engines; Heating and 

Ventilation; Refrigeration. 
10c Machine Design and Mechanism; Power Transmission; Steam 

Power and Power Plants; Thermodynamics and Heat Power. 
11 — Mechanics. 

12 — Medicine. Pharmacy. Medical and Pharmaceutical Chem- 
istry. Sanitary Science and Engineering. Bacteriology and 

Biology. 

MINING ENGINEERING 

13 — General; Assaying; Excavation, Earthwork, Tunneling, Etc.; 
Explosives; Geology; Metallurgy; Mineralogy; Prospecting; 
Ventilation. 



V 



cA 






i j 



lun iGRAPHICAL MAP 

GE - T TYSBURCi — ANTETAM 








if 


8 


1 




1 






91 

; 


| 







